Introduction of a yeast with rum aptitude in fermentation of sugar cane derivatives

Vidal F., Parfait A., 1994. Introduction d’une levure à aptitude rhumière en fermentation de dérivés de la canne à sucre. BIOS Boissons 249, 21–26. [My translation]

Introduction of a yeast with rum aptitude in fermentation of sugar cane derivatives
by
F. VIDAL* et A. PARFAIT**
* Centre Régional d’Innovation et de Transfert de Technologie-Biotechnologie et Agro-industries de la Caraïbe, BP n° 52, 971.52 Pointre-a-Pitre, GUADELOUPE FWI.

Summary

Rum is the most consumed white alcohol in the world. Among the different types of rums, traditional rums are all produced in the French overseas departments. In the French West Indies, rum technology has changed little. In distilleries, the largest losses happen in the fermentation workshops. Since the opening of the European market, the protection of French rums is less important and competition is becoming worrying. The reduction of losses and the regularity of production should allow local manufacturers to remain competitive. In this context, better control of the operations in the fermentation plants has become necessary. In the INRA yeast collection, a 493 yeast, adapted to the medium based on sugar cane gives interesting results in industrial distilleries. With very precise implementation conditions using an active dry yeast seeding technique, alcohol productivity gains can be estimated at 30%, which will have a direct impact on the cost price of rum. The working conditions at the factory will also be improved.

The diffusion of yeast 493 with its seeding technique is now acquired for the production of molasses rums. In an agricultural distillery, the problem is more complex because it is necessary to take into account the interactions between yeast and bacterial activities.

Introduction

Rum is the third most consumed spirits in the world. With more than 500 million liters of pure alcohol a year, it occupies 11.4% of the market on a par with liqueurs but after whiskeys (28%) and brandies (14%). The first white spirit consumed, it is progressing steadily in a global manner and remains, on the commercial front, an issue for the large multinational companies of brandies (1).

In the French West Indies, rum fermentation has been traditional since the 17th century; different types of rums are produced according to the raw material used. Their technical itineraries are presented on the diagram no. 1 (2). As provided by French legislation, they all come from a fermentation and distillation of cane juice or molasses or syrup from the manufacture of cane sugar. From a regulatory standpoint, rums must also meet “impurity” or non-alcohol content (ENA) levels that are presented in Table 1.

Currently, on the market, rums of molasses occupy a predominant place and more particularly so-called light rums; they are rums refined by extractive distillation which gives them a very neutral taste. They are then used for blends.

Agricultural rums are produced exclusively in the French overseas departments and may be subject to special protection with the establishment of a controlled designation of origin. Even if traditional rums production seems marginal, they remain very popular on the French market for their aromatic character.

State of the rum technology in Guadeloupe

In Guadeloupe, the annual production of rum is about 8,000,000 liters of pure alcohol (IPA) for 12 distilleries, which represents a significant component in the profitability of the sugar cane sector. The capacity of industrial units varies from 70,000 to 700,000 IAP for industrial distilleries ((3), (4)).

Rum technology has evolved, but among the main manufacturing stages, fermentation is the one that is the least controlled and that generates the most significant losses.

The fermentations are either spontaneous or activated by a complementary seeding of baker’s yeasts. They are carried out in 48 hours on untreated musts containing 90 to 140 g/l of sugars and giving wines containing 4 to 6.5% volume ethanol. Only nitrogen addition and acidification of the medium are carried out.

Seeding fermentation tanks is carried out according to different techniques: the process by tank-mother (generation of leaven on medium more or less aerated with concentrations in sugars close to 80 g/l), the bottom of tank (addition fresh must on a volume of wine not sent for distillation, rich in yeasts) and the cutting from a tank in the active phase of fermentation.

Whatever these techniques, the conditions for the implementation of leaven are poorly controlled and fermentation controls during manufacture are, when they exist, difficult to interpret.

The introduction of yeasts from bakeries (Saccharomyces cerevisiae) recommended in 1969 by MEJANE has made it possible to limit fermentation accidents but the ethanol yields obtained in distilleries are still low. Expressed in liters of alcohol per kg of reducing sugars, they are 0.52 for molasses and 0.47 for cane juice, whereas the theoretical yield according to PASTEUR is 0.643 IAP / kg (5).

According to TOURLIÈRE (6), a well conducted alcoholic fermentation should lead to a yield at least equal to 0.60 IAP / kg and any distiller should be able to get closer to this practical yield. ALARD and DE MINIAC (7) obtained yields of 0.62 IAP / kg on beet molasses.

Alcohol losses are expensive for distillers because they have a direct impact on the cost of rums, which are very high in the West Indies compared to other producing countries.

In this context, the introduction of a yeast adapted to rum fermentation was raised. The objectives are multiple: increase control of fermentations, reduce ethanol losses, limit bacterial contamination and improve working conditions in the distillery.

Introduction of a yeast selected distillery

We used yeasts from the INRA collection that were all isolated in production sites before the systematic introduction of baker’s yeasts.

During the laboratory selection, a Saccharomyces cerevisiae listed 493 was most active during the initial fermentation phase of cane juice and molasses with an interesting ethanol yield. These results were confirmed when comparing this 493 yeast with other commercial yeasts, including baker’s yeast used in the distillery (8).

Properties of yeast 493

A methodology has been put in place to characterize the strain at the microbiological and biochemical level, to compare its fermentative performances with those of other yeasts, and then to define the conditions for industrial implementation in the form of active dry yeasts. The goal is to make the most of the fermentative potential and technological interests of this strain. The work was carried out at three stages: laboratory, pilot and industrial.

 

 

The company LALLEMAND has been associated with these operations in the context of the production of strain 493 active dry form and in the comparative study of this yeast with yeasts of various origins belonging to their colleciontion

At pilot scale on molasses medium, experimental conditions have been established with reference to industrial conditions (9). We first validated the first results obtained on the capacities of the strain 493. Presented in the table no. 2, they show that the strain 493 has interesting fermentative potentialities on these media. Compared to baker’s yeast, Yeast 493 gives a yield and an ethanol productivity which are respectively 6.5% and 18.2% higher. The alcohol yields expressed in IAP / kg of reducing sugars observed confirm that the experimental conditions are close to the industrial reality since we obtain a yield of 0.524 for the baker’s yeast (corresponding to the figure announced at the industrial level).

To confirm the strong performance of yeast 493, a new comparative study was set up at the laboratory stage. Yeasts from the LALLEMAND collection have been selected according to their properties, either to withstand high temperatures or to support high osmotic pressure media such as strain no. 46 isolated by DE MINIAC from the National Union of Alcohol Distillers (10).

The results in table no. 3 confirm the previous outside observations. Strain 493 with yeast no. 46 are the most adapted to these types of environments; they give the best fermentation results. As a result of fermentation, the population level of strain 493 is very high, suggesting that its establishment and maintenance will be facilitated at the industrial level.

From a biochemical and microbiological point of view, the yeast 493 is a Saccharomyces cerevisiae var cerevisiae killer vis-à-vis the strain S6 and neutral to the strain 522D (toxin K2). Its pH and its optimum temperature. The growth rates are 4.5 and 33°C, which corresponds to the average fermentation conditions in the distillery.

The fermentative behavior of yeast 493 has been more specifically studied according to the density and temperature parameters which represent industrial constraints.

In distillery, the vat room is rarely equipped with cooling systems and it is common to note temperature rises reaching 36 to 37°C at the end of the exponential phase of fermentation. This lack of temperature regulation also conditions the low values of the initial densities of musts (1070).

Table 3- Comparison of yeasts in molasses fermentation at the laboratory

Table 4- Comparison of the serological balance between two processes: mother vat / baker’s yeast; pre-fermentation tank / yeast 493

Yeast 493, for controlled fermentation temperatures at 30, 33 and 36°, retains good yields of alcohol (Figure 1). On the other hand, the ethanol productivities decrease by 18.5% when one goes from 33 to 36 ° C, because at this temperature, there is a slowing of the sugar consumption at the end of the fermentary phase (figure no. 2).

This yeast also produces, for musts with a concentration of sugars of 185 g/l (density 1102), wines grading up to 9.1% ethanol volume without modifying the yield of alcohol. Even if a drop in productivity of 20% is observed when passing sugar concentrations from 120 to 185 g/l (Figure 3), the operating time of the distillery would be significantly reduced (about 30%).

Due to its background, yeast 493 appears to possess a genetic ability to grow on sugarcane-based environments. By introducing this yeast, accepting both high temperatures and high osmotic pressures, the operating times of the plants could be reduced.

Yeast seeding technique

From an industrial point of view, the seeding technique is important both for the progress of the fermentation and for the quality of the rums.

In a molasses distillery, the most common seeding technique is the mother tank, which is used to generate a leaven. With this method, the amounts of yeast used in dry form are low; population levels and qualities of starters are not controlled as are the risks of contamination.

While considering the financial criterion, we recommended, after a series of pilot level trials on seeding techniques, a process that takes into account biological phenomena (yeast requirements, quality and quantity of leaven, implantation of strain, reduction of contamination) and working conditions in the distillery.

This process consists in replacing the mother vats with pre-fermentation vats which, when seeded at rates of 0.5 g/l with active dry yeasts, make it possible to obtain quickly a high level of high quality population. After fermentation (about 25% by volume), the progressive filling of the fresh must protects against excessive temperature rises which will directly affect the productivity of ethanol.

Figure 2-influence of temperature on density drop

Figure 3 – Influence of density on productivity and ethanol yield

Industrial tests

We conducted a week of trials in industrial distillery on the whole of the vat room which represents 24 fermentation tanks of 130 m³ each is the production of 190,000 IAP. Yeast 493 yeast / pre-fermentation tank gives very satisfactory results (Table 4). Alcohol yields (0.595 IAP / kg of fermentable sugars) have increased considerably. The average alcohol content of molasses wines of 6% ethanol volume (for a concentration of sugars of 100 g/l) is very reproducible with a coefficient of variation on the whole of the vat room of 2%. It can be estimated that between the gains obtained on the alcohol yield (14%) and on the occupation time of the vats (-17%), the total productivity gain of the plant will be greater than 30%.

Implantation and maintenance of strain 493, followed by pulsed-field electrophoresis chromosome migration technique (11), is greater than 90% at the end of fermentation with a 100% viability rate persisting during the first waiting phase before distillation.

From a qualitative point of view, the triangular tasting tests carried out with a jury of consumers show a homogeneity between the different batches of rums produced with the yeast 493. Compared to the rum produced with the baker’s yeast, it has a taste and a Balanced aroma with no bad taste.

Conclusion

The introduction of selected yeasts in rum fermentation is of interest only if it brings a reduction of the losses in the fermentation workshop and a better functionality of the factory. This is the case of the process that we recommend (use of pre-fermentation tank with seeding of yeast 493 in dry form activated) which gives good yields of alcohol and interesting gains in terms of productivity in industrial distillery which will have a direct impact on the cost price of rum. The organization of work in the fermentation workshop will be facilitated with the use of a single wort at a constant density and a rational adequacy between the preparation of the pre-fermentation tanks and the fermentation tanks. The risk of contamination is minimized by the lack of mixing of the tanks between them and the production should be regularized both quantitatively and qualitatively.

Even if the recommended process uses larger quantities of active dry yeasts than the conventional one, it can be estimated that, in the case of the distillery as an industrial support point and in its current operating conditions, the financial burden supplement should not exceed 10% of the profits obtained with the combined use of yeast 493 and the new seeding process.

Similar studies on cane juice are currently underway. A methodology on the seeding technique should be proposed to distillers respecting both the aromatic quality of agricultural rums and the reduction of ethanol losses. Here, the case is more complex because the fermentation results from an association of yeasts and bacteria responsible for the aroma so much sought after by informed consumers; this situation must be taken into account.

Thanks

We thank LALLEMAND SA, which gave us the benefit of its expertise in the introduction of selected yeasts in fermentative environments and which supported this work by taking charge of the development of industrial production technology in active dry form for yeast 493. Miss RAGINEL be thanked for her assistance in the comparative studies between yeast 493 and those in their collection.

Our thanks go to Prof. STREHAIANO and P. TAILLANDIER from ENSIGC’s Bioengineering Engineering Laboratory in Toulouse for their welcome and their technical and scientific supervision during the implementation verification studies of yeasts in industrial sites.

We thank Professor GOMA and his collaborators from the Department of Biochemical and Food Engineering of INSA Toulouse who have put the laboratory equipment at our disposal for some work.

We thank the distilleries of Guadeloupe who have made available their facilities for work on an industrial scale.

This work was funded in part by European support from the STRIDE Community Initiative Program.

Bibliographie

(1) (1993). — Le rhum : un marché potentiellement très concurrentiel. Revue de l’union patronale de la Guadeloupe, décembre, 12-16.

(2) PARFAIT A., SABIN G. (1975).– Les fermentations traditionnelles de mélasse et de jus de canne aux Antilles françaises. Ind. Alim., 92. 1,27-34.

(3) RANCE H. (1992). — Étude technico-économique de la filière rhum aux Antilles françaises. Rapport de stage CRITT-BAC Guadeloupe. IUT La Rochelle, 52 pages.

(4) (1993). — TER Guadeloupe, éditeur direction interrégionale INSEE Antilles Guyane.

(5) DESTRUHAUT C, FAHRASMANE L, PARFAIT A. (1986). — Technologie rhumière. Rapport de fin de convention INRA/Distillerie St James.

(6) TOURLIÈRE S. (1985). — L’éthanol de fermentation : ses possibilités, ses limites. Ind. Agric. Alim., 6, 749-753.

(7) ALARD G., DE MINIAC M. (1985). — Recyclage des vinasses ou de leurs condensats d’évaporation en fermentation alcoolique des produits sucriers lourds. Ind. Agric. Alim., 102,9,877-882.

(8) FAHRASMANE L. (1991). — Amélioration du rendement de la fermentation alcoolique sur milieu à base de canne à Sucre. 1° rencontre internationale en langue française sur la canne à sucre. Montpellier, France.

(9) VIDAL F, BONNEAU L., PARFAIT A. (1993). —Yeast and rum production: survey of some trials. Congress & Distilled beverage industry – Fermentation – Technology, 21-25 mai, Orlando, Etats-Unis.

(10) DE MINIAC M. (1987). — Sélection de souches de levures pour la fermentation alcoolique de milieux mélasses enrichis en nonsucre de vinasse. Ind. Agric, Alim, 5,425-439.

(11) BLONDIN B., VEZHINET F. (1988). — Identification de souches de levures œnologiques par leurs caryotypes obtenus en électrophorèse en champ pulsé. Rev. fr. oenol., 28,7-11.

Contribution to the bacteriology of manufacturing waters of Guadeloupe distilleries.

Ganou-Parfait B., Valadon M., Parfait A., 1991. Contribution à la bactériologie des eaux de fabrication de distilleries de la Guadeloupe. AFCAS : 1re Rencontre internationale en langue française sur la canne à sucre, 296–302.

Contribution to the bacteriology of manufacturing waters of Guadeloupe distilleries.
by
GANOU-PARFAIT B., VALLADON M., PARFAITA.
INRA, LAPRA, CRITT-BAC, Pointe à Pitre, Guadeloupe

Summary

Water resources have two main origins: rivers and groundwater. The inventory of the bacterial microflora is oriented towards the search for germs that may have consequences in manufacturing.

Several factors influence the quantitative and qualitative composition of the bacterial population: thermal processes, mineral content and the use of antiseptics. Results are provided for some industrial sites.

Keywords: distillery, rum, bacteria, water, mineralization, contamination, antiseptic.

The distilleries of the Guadeloupe archipelago are located in three islands: Basse-Terre, Grande-Terre and Marie-Galante. The last two are characterized by a dry climate and calcareous soil. The water table and small rivers constitute the own water resource. Basse-Terre is mountainous and humid; surface waters are more abundant.

Manufacturing waters are not treated, they bring with the raw materials, most of the germs of contamination. To protect fermentative media from bacterial growth and activity, acidification is caused by sulfuric acid and certain fluoride-based antiseptics are used.

The bacterial flora also participates in the formation of the aroma.

Materials and methods

Water samples are taken at the feed of the industrial site. The operation continued for two seasons, 1989 and 1990 for a period from February to May. The treatment scheme is that of Figure 1. The different groups of bacteria are isolated from selective media (Table I). The counts of certain anaerobic bacteria, including sulphate-reducing bacteria are made according to the most favorable number method with a 95% confidence coefficient (ALEXANDER, 1982) and for this purpose on three tubes by dilution.

Other bacteria are counted by the Sartorius membrane filter method. The water is diluted and filtered on a filtration ramp. The filtration membranes for counting cellulose nitrate have a porosity of 0.2 μ and are then applied to the agar medium agar plate. The incubation takes place at 30°C for aerobic germs and gaspak jar at 30°C for anaerobic germs.

The determination of the minerals of the water samples was carried out by HPLC; these are first filtered under vacuum to facilitate degassing. After dilution, the samples are clarified by passage over Sep-pak columns. The anions are separated by passing through a Mitsubishi SCA03 column at room temperature with potassium phthalate eluting at pH greater than 8. They are analyzed on the universal UV detector JASCO 875 uv. The cations are separated by passing through a Mitsubishi SCK 01 column at room temperature. The eluent for alkalis is nitric acid and for alkaline earths is tartaric acid supplemented with ethylene diamine. They are detected by a WESCAM 215 conductivity meter. Figure 2 shows examples of separation. The different ions are quantified and recorded thanks to the integrator SIC calculator: Chromato corder 12.

Results

From a bacteriological point of view, there are aerobic germs (lactic acid bacteria, corynebacteria, Bacillus) more present in cane juice-based media and thermophilic and anaerobic germs (clostridia, Bacillus, sulphate-reducing bacteria) more abundant in molasses media (Table II). Antiseptics are used in the distillery to limit the activity of bacteria. The most commonly used is sulfuric acid (41/100 hl); it makes it possible to lower the pH of the meal to 4.5, but increases the concentration of sulphate ions in the fermentation medium.

It is possible that the metabolism of sulfur in yeast and in bacteria (BSR) has consequences on the aromatic fraction of rum and the quality of vinasses, a source of pollution on the environment. Other antiseptics have been used in Guadeloupe.

Quite often, besides the necessity of adapting yeasts to these antiseptics, resistant bacteria develop.

Table III: The waters of the rivers. Variation of mineral contents.

Laboratory tests have shown that bacteria in fermentative fermentation media can grow in the presence of high concentrations of sodium fluoride (0.28 g/l), sodium acid, sodium chloride and ethanol. This indicates an adaptation of bacterial germs to sodic antiseptics, to ethanol (up to 8 °GL in general) We have studied the variation of the manufacturing water contents in ions sodium, calcium, magnesium, chloride, nitrate and sulfate and the variation of the corresponding bacterial flora (Tables III, IV, V and VI).

 

Table IV : Variation of the bacterial flora in the water.

Aerobic bacteria

Lowland
At the beginning of the febriermars campaign, their number is of the order of 7.10^6 bacteria / ml of water then it regresses and stabilizes until the end of the campaign at 6.10^3 bacteria / ml

High land
At the beginning of the campaign it was possible to detect 1.10^3 aerobes / ml of water. This number remains stable during the campaigns except in April when it increases slightly to 1.10^4 bacteria / ml

Marie-Galante
In March, we detected 1.10^3 aerobic bacteria in the river water. In April they are of the order of 15.10^4 on average. Storage in concrete tanks shows an increase in aerobic flora: 11.10^6 bacteria / ml of water in April

Anaerobic bacteria

Lowland
The rains of April seem to favor the number of anaerobic bacteria, generally stable during the campaign. The population goes from 1 to 6.10^3 to 1 to 5.10^5 bacteria / ml

High land:
The water contains few anaerobic bacteria at the beginning of the campaign: 1.10^2 bacteria / ml in 1989, 2.10^4 bacterias / ml in 1990. We detected periods of strongest contamination as in March 1989 (Easter): 2.10^4 bacteria. At the end of the 1990 campaign, the number of anaerobes reached 5.10^4 bacteria / ml

Marie-Galante
We observed an increase of the anaerobic flora in time during the campaigns, it went from 10^2 to 10^4 bacteria / ml of water. However, the number has increased in the deep steel tank as it has decreased in the reservoirs, very wide and shallow concrete ponds: 50 to 100 bacteria / ml

Spore-forming bacteria

Lowland
The number of sporulated bacteria declines from beginning to end of the season. It goes from 10^3 to 10^1 bacteria for anaerobes and 6.10^2 for aerobes

High land:

Their population decreases during the campaigns. The sporulated anaerobes remain few: 4 to 7.10^1 and are not found in the countryside. Spore-forming aerobes are rarer. We observe a maximum in April of the order of 10^1 bacteria / ml

Marie-Galante
Spore-forming anaerobic bacteria are rare in water. Their number is around 6 to 10 in the tanks. Aerobic spore-forming bacteria increased in April from 10 bacteria / ml to 1.10^6 bacteria / ml

Sulphate-reducing bacteria

Lowland
The first months of the industrial campaign made it possible to count 1 to 2.10^2 bacteria / ml. This number of bacteria evolves by regressing the following months until being canceled at the end of the campaign

High land
Bacteria are generally in small quantities except at periods of a kind of contamination (March 1989 for example): 10^1 to 2.10^3 bacteria / ml. At the end of the campaign, we do not detect any more.

Marie-Galante
Their population is generally non-existent except in April: 10.10 bacteria / ml. At this same time their number is, in the steel tank, 2.10^2 bacteria / ml

Depending on the geographical location and the type of water, we note quite large differences between the diluting waters of the distillery raw materials.

The groundwater of Grande-Terre and Marie-Galante are in contact with seawater at certain times of the year. This probably explains the high chloride, sodium and sulphate contents of these waters. Well water from Marie-Galante has larger amounts of sodium, calcium, magnesium, chloride and sulphate than well water from Grande-Terre. It contains in addition nitrate.

Table V: Variation in Mineral Content in Well Waters (There was no well on the lowlands.

Table VI: Variation of the bacterial flora of well water.

Surface water is less mineralized than well water. The reserve water of Grande-Terre is equivalent to the mineral of Basse-Terre; it is in fact from this that the irrigation water of Grande-Terre is conveyed.

The bacterial flora of Basse-Terre, Grande-Terre and Marie-Galante surface waters are similar; however, we note that Grande-Terre’s irrigation water is a little richer in anaerobic bacteria and sulphate-reducing bacteria. The river water of Marie-Galante sees its flora vary quantitatively when it is stored. Masonry ponds seem to favor an increase in bacterial flora especially if they are poorly maintained and deep.

The well waters of Marie-Galante are more contaminated than the well water of Grande-terre; only the population of sporulated bacteria appears more numerous in the water of Grande-Terre. All these results show that there is a certain relationship between the mineralization of manufacturing waters and their bacterial population. Well waters that contain high concentrations of minerals are more contaminated by bacteria than surface water. It is difficult to say that this or that ion is responsible for the variation of the population of this or that bacterial group for the moment. We have simply found, for example, that in the brackish waters of the groundwater there are groups of BSRs, one of which has a halophilic tendency and that in some waters the decrease in time of concentration of sulphate ions corresponds to an increase in the number of SSBs.

Bibliography

ALEXANDER. M., 1982. Most probable number method for microbial population. Methods of soil analysis part 2. Chemical and Microgiological poperties. Agronomy monograph n’ 9 (2nd édition), p. 815-820

ANON, 1985. Standards methods for the examination of water and wastewater 16th edu. Washington D.C. American Public Health Association.

Jonscher A. For the knowledge and evaluation of rum, Rumverschnitten and Kunstrum. 1914

Jonscher A. Zur Kenntnis und Beurteilung von Rum, Rumverschnitten und Kunstrum, Z. Öffentl. Chem. 20 (1914), p. 329-336, 345-349.
For the knowledge and evaluation of rum, Rumverschnitten and Kunstrum
[untranslated German]

This paper is no block buster and the translation is not my best, but we can cross it off the list. It will probably interest few so I’d skip to the conclusion where the work of Karl Micko is discussed. The end adds a little bit to the debates of where that peculiar aroma comes from in rum. Jonshcer likes Micko’s eight fraction technique but not some of the other ideas Micko had. Some cryptic citations are given that may point to more of Micko’s work. I did republish his English language papers, but it would be useful to see if the foreign language papers are different.

A big takeaway is that lots of organizations were interested in spirits analysis for various purposes like fraud detection. The importance of various congeners and their ratios was being investigated relative to organoleptic assessment. They were even starting to weight the importance of ester counts knowing that much of the number was just ethyl-acetate.

For the knowledge and evaluation of rum, Rumverschnitten and Kunstrum.
From Dr. A. Jonscher, Zittau.

In 1912, the author of this article at the 17th General Assembly of the Association of Independent Public Chemists of Germany in Dusseldorf was able to bring his experience of the brandy “Cognac” to the general knowledge; Experiences that are already significantly expanded today and cause them to follow suit as soon as possible.

On the other hand, a second brandy, and indeed the rum, with its descendants, received proper attention and analytical research, which may be described in detail later.

From the literature, the following will first have to be present with reference to the characteristic components of rum:

Eugen Sell (Arb. Kaiserl. Gesundh.-Amt 1891, B. 7, S. 210.) has shown by examination of Jamaika rum, Cuban, and Demerara rum that the volatile acids contained therein consist chiefly of acetic acid, which considerably retreats to the contents of formic acid, butyric acid, and capric acid, and about equally 1/13 amounts to. In the case of the esters, the acetic acid ethyl ester then occurs about 12 times as much as the formic, butyric and capric acid ethyl esters taken together, which by the way are approximately in the ratio of 5:2:3.

K. Windisch (Arb. Kaiserl. Gesundh.-Amt 1893, B. 8, S. 278.) examined Jamaica, Cuba and Habanna rum distillates, taken by official means at the place of extraction, in the same way as Sell and found that there are Jamaican, Cuban and Habanarum, which are neither free Formic acid still contain formic acid ethyl ester. However, all show a strong salient acetic acid and acetic acid ethyl ester content in addition to the already butyric acid- and capric acid amounts and their ethylene ester shares.

In any case, the more frequent presence of formic acid and formic acid esters suggested that in real rum, in addition to ethyl alcohol, some methyl alcohol was also present, from which formic acid, etc. were oxidized by oxidation. Esterification emerged. This question was solved by Trillat and Quantin (Journ. de Pharm. et de Chim. 1900, S. 505; Pharm. Centralh. 1903, S. 12. ), the latter by using particularly large amounts of rum that the rum is always naturally free of methyl alcohol, which fact has also been confirmed by HC Prinsen-Geerligs (Chem. Zeitung, 1908, S. 70, 79, 99.), who concludes that The formic acid, which is often present in rum, must have been produced directly from glucose, at least not related to any methyl group in the sugar cane.

Th. Von Fellenberg (Mitt. aus dem Gebiete der Lebensm.-Unters. u. Hygiene veröffentl. vom Schweiz. Gesundh- Amt 1910, B. 1, S. 352.) has dealt with the nature of the higher alcohols of rum and, on the basis of his examinations, has come to the conclusion that they consist essentially of n-butyl alcohol. Further investigations are missing completely. But one may well with the statement Fellenberg’s opinion that it concerns the rum. The ratio of the higher alcohols to each other may be similar to that on the other hand (Zeitschr. f. öffentl. Chemie 1912, S. 421.) for cognac.

As far as the numerical analytical investigation of the rum is concerned, the following works are to be cited in this direction, which at the same time may set forth the development of rum analysis.

A. Skala (Atti della R. Academia Medica di Roma 1890.) and A. Herzfeld (Zeitschr. Zuckerindustrie 1890, B. 40, S. 645.) restricted their determination of the total amount of volatile acidity and esters in their numerical investigations to the determination of alcohol, extract and mineral content. E. Sell went one step further and also determined the closer composition of the acid and ester quantities. K. Windisch also considered the fusel oil content in addition to the investigation of the mass of individual acid and ester constituents. However, since he worked in the latter respect according to the Röse method, which almost always gives erroneous results in rum according to more recent experience, his reports on the fusel oil content of Jamaica, Cuba and Habannarum have only development-historical value.

There it was to be regarded as a noteworthy advance, as E. Beckmann (Zeitschrift f. Unters. d. Nahrungs- u. Genussm. 1899, S. 708.) for the determination of the higher alcohols in rum, etc. stated an exact method according to which the fusel oil first salted out by added calcium chloride, shaking with carbon tetrachloride, esterified with nitrous acid, and finally the nitrogen thus bound was determined volumetrically.

The newly examined type of investigation and form of publication, however, possessed defects in many directions. On the one hand, it was not extensive enough, and then the results were always given according to the different alcoholic strengths, which of course lost most of the orientational value. Meanwhile, however, a change had already begun for the better. Although E. Mohler (Compt. rend. 1891, B. 112, S. 53; Chem.-Zeitg. 1891 Rep. S. 13.) published the results of his Jamaikarum study for the corresponding alcohol strength, he already extended his investigations to volatile acidity, esters, aldehyde, furfurol, and fusel oil. Later, Lusson (Monit. scientif. 1896, B. 10, S. 785; Vierteljahrsschr. Nahrungs- u. Genussm. 1897, B. 12, S. 264.) first used cognac as a groundbreaking form of calculation for all alcohol constituents of 100 cc. absolute alcohol also for rum products of all kinds full application, d. H. From then on, the values ​​for volatile acidity, esters, aldehyde, furfurol and higher alcohols were determined at each scientific rum test and calculated for 100 cc of absolute alcohol, with the determination of aldehyde, furfurol and fusel oil simplified by colorimetric methods.

Now, if the analytic experiences about the different products of the rum producing countries are to be brought to the table in the following and all for 100 cc of absolute alcohol, then the test results of Windisch have to be put off in any case.

These investigations by Windisch (Arb. Kais. Gesund-Amt 1893, B. 8, S. 278.) with samples of Jamaika, Cuba and Habannarum carried out, even by official mediation (at least by consular officials) at the place of extraction itself, may therefore seem to some as particularly valuable, which also in this direction should not be disputed. However, on the other hand, in the name of the specimens or their design, there have been such gross deficiencies, especially at the time of this sampling, that the test results of these specimens are rendered completely unusable for a summary table of the composition of rum by trade; These samples are undoubtedly not exports, but merely intermediate production patterns from various distilleries in Jamaica, Cuba, and Habana. This can be seen from the fact that the alcohol content of the samples fluctuates from 53½ to 95½ vol.%, Although that of the export is constantly around 75 vol.%. Further, the two Jamaika rums that were present were the opposite of each other. One is an unusually aromatic product with 2499.0 the other with only 93.1 ester number. In general, fluctuations in the Habannarum were not so great; after all, the composition of these samples can also be explained as conspicuous enough. Finally, the Cubarum also had products with acceptable ester numbers as well as such a particularly low-flavor character. Finally, there are still 2 products that have an alcohol content of 95½ vol.% At an ester number of only 6 and 9, so from the usual framework of rum composition out that it is certainly sugar cane molasses alcohol under any circumstances but Cuba rum can act.

The following overview tables bring the literary experiences first of all over the Jamaika rum, which is most widely traded in Germany; followed by Cuba- and Demerara rum. After this, the products of the French colonies Martinique, Gouadeloupe and Réunion arrive for illustration. The number of analyzes carried out by the individual researchers is enclosed in parentheses or otherwise identifiable.

(13) Zeitschr. Nahrungsm-Unters, Hyg. u. Warenk. 1895, B. 9, S. 317.
(14) Journ. Chem. Soc. Ind. 1907, B. 26, S. 496.

So far, the literature with its experiences, according to which our knowledge of rum are certainly not as insignificant.

Now, in 1891, E. Sell, following his rummaging work, liked to make the statement, cited in particular in relevant circles of commerce and on every occasion, that in the ruling on the ruling, the best choice would be given to such an expert taste and smell sample. “This sentence was allowed to claim validity at Sell’s time, but today it is completely without authorization. In Sell’s times (thus 23 years ago) the chemical rum knowledges, as well as the above explanations clearly enough show, so in the error, that of a correct chemical evaluation could not be the question, and the soon appearing work of Windisch with the mentioned officials had to just increase the uncertainty only. Today, on the other hand, our chemical knowledge in the area of ​​the rum areas is so extended and fortified that the experts are no longer those who can only smell and taste, but rather those who, in addition to a trained tasting, at the same time individually taste the odors and flavors themselves determine and prove. But that is only possible for the food chemists equipped with special exercises, as the preceding and following general reports teach on their own.

Echter Rum. [Real rum.]

When discussing the food chemistry assessment of true state-of-the-art rum, it must first be stressed that rum is a peculiar fermentation and distillation product, with both fermentation due to deviance in different countries as well as distillation depending on the design of the still and after the cutting process a number of differences conditionally, can never be absolutely equal. Thus, better and lesser products occur naturally, and on a fully natural basis, more often than in other foodstuffs. Therefore, the French chemists and the French trade in accordance with the approach of Bonis and Simon divide the real Rum sold there into three classes, which they according to the aroma d. H. delineate according to the amount of the Lusson Girard numbers in the Martinique rum, which is particularly popular in France, as follows:
Type supérieur 550–900
Type moyen 450–550
Type inférieur 350–450

The English chemist Williams, and with him the English trade, distinguishes only two qualities in the Jamaika rum, which is most in demand in England and Germany, which are also distinguished by the aroma and the Lusson-Girard numbers:
Ordinary Jamaika rum 300-550 Fine aroma.
Jamaika rum 550-1000

These natural differences in quality can not be avoided in the German trade, because they are also represented here, as 6 by the author in association with Dr. med. M. Groneberg examined real Jamaika rums from public transport:

The question of quality always has to be answered first in the case of rum with the analytical documents that have been determined, since it also plays an outstanding role in practical trade. The only question is whether the current type of evaluation with the Lusson Girard numbers can be recognized as completely flawless and strictly fair. But this can not be added for all cases, because
a) Furfurol has hardly any flavor value at all,
b) the acetic acid probably has a conditional taste value but no aroma value,
(d) the higher alcohols have only a slight flavor and flavor value, but become directly harmful in the case of greater prevalence and produce the unpleasant “Blasengeschmack” [alembic taste] according to Simon;
e) thus the esters and aldehydes alone may be considered as wholesome flavorings.

If this is the case, it is impossible to sum up the number of parts found according to Lusson-Girard, and then to sum up the sum definitively and determine the quality; for it will often happen that particularly pungent and acetic acid-rich rum products, which must almost be regarded as defective in taste and originate from a deficient distillation process, are valued particularly favorably, which is certainly not intended. At any rate, however, such errors are avoided if the number of pieces calculated according to Lusson-Girard are put together as follows:
1. Aldehyde and esters are used with the fully weighted Lusson Girard values; the same thing can be safely done with furfurol, since its low levels of presence are never able to make a difference;
2. Acetic acid and fusel oil, however, according to modern experience, which suggest a decrease and a purer distillation in the production areas, are brought to the summation at only 75; the plus or minus of the actual determination of these 2 bodies is then simply put to disposal in the closer appraisal.
3. For quality 1, the rum varieties are to be counted, which with the indicated valuation amount over 550, to quality 2, finally, those, which are below 550.

The 2 different Jamaika rum series analyzed by W. C. Williams receive here with their averages the following expression form:

This expression clearly shows that these are 2 different qualities, since the score is 944 in one case and 536 in the other; but it also continues to prove with the plus and minus additives that in both cases there are no defective distilled products, since the deviation from the modern normal content in acetic acid and fusel oil is only relatively small.

Rum verschnitt. [Rum blended.]

After these explanations on the quality question and the basis of evaluation of real rum may now also come to the assessment of the rum products, which were mixed with purified spirit. Again, with the Lusson-Girard payment, you are able to provide all the information you need, especially when (as in the case of whole milk samples) a control sample of the rum that is supposed to be used for the blend is used. As the rum blends now contain almost all more purified spirit than Jamaica rum, etc., it goes without saying that a closer knowledge of how this spirit generally behaves in the Lusson-Girard affirmations is very appropriate. For this reason, first of all, a work by Girard and Cuniasse (conf. X Rocques, Eaux de vie, Paris 1913, S. 179.) on 13 samples of French industrial spirit is presented in tabular form in the literature:

After this the German industrial spirit with 2 investigations of the author and Dr. med. M. Groneberg from 1914 to illustrate:

With this knowledge also important. In view of the nature of the purified industrial spirit, it will now be possible to approximate the respective content of real Jamaicarum slightly in the case of the rum blends in commerce, as will be shown by examples from this worldly practice.

For the more precise assessment of the content of real Jamaica rum, it is not necessary to use the analytically found Lusson girard values for the high-quality blends which (as in 4805 and 68) reveal themselves with a higher aldehyde content deduct from Lusson girard numbers, because these parts are of little importance in such blends; but in the case of low value cuts, which as such also characterize the aldehyde number, this withdrawal is essential and may include, without significant error, the full average value for purified industrial spirit. In this procedure one obtains in the 4 last Rumverschnitten above table, which are to be considered alone as low-grade in this sense, since they can expect only about 10 to ½% Jamaikarum, the following number of rumor indicating number of Lusson-Girard:

Since the average Lusson-Girard number for the Jamaicarumqualitaten 1 and 2 according to W. C. Williams 771.3 addition to an aldehyde and ester content of 18.0 bezw. 567.5, we now arrive at the Jamaikarum contents of the above 6 sample cuts on the following basis of calculation and calculation:

Sample 4805 shows a Lusson Girard number of 224.5 with an aldehyde and ester content of 9.3 and 171.6 respectively. The mutual relationship of these numbers is quite normal and leads to the equation: 771.3: 100 as 224.5: x equals 30% Jamaika rum.

Sample 68 shows a Lusson Girard number 254.2 at an aldehyde and ester content of 80 and 193.6 respectively. The mutual relationship of these numbers is again normal and leads to the equation: 771.3: 100 as 254.2: x equals 33% Jamaika rum.

Sample 138 shows a corrected Lusson-Girard number of 81.8 at an aldehyde and ester content of 3.0 and 44.0 respectively. The ratio of these numerical parts is again normal and leads to the equation: 771.3: 100 as 81.8: x equal to 10% Jamaika rum.

Sample H shows a corrected Lusson Girard number of 74.0 at an aldehyde and ester content of 1.5 and 60.9 respectively. The ester content is here in comparison with aldehyde, acid and higher alcohols and clearly shows that a particularly high-ester Jamaika rum was used for the blend, the ester content was certainly about 1/3 above the usual average mass.

For the correct calculation, the average Lusson girard number of the Jamaica rum of 771.3 must therefore either be 1/3 of its ester amount d. s. 189.2, or the Lusson Girard number of the test sample is reduced by 1/3 of its ester amount, which means the same. In the case of the latter form of calculation, the following equation then results: 771.3: 100 as 53.7: x equals 7% Jamaika rum. The manufacturer later admitted that only 5% Jamaica rum was used for Sample H.

The sample P. 36 shows no aldehyde content at all and can therefore contain only a negligible amount of real Jamaica rum. It was therefore declared to be deceptive in the sense of § 10 of the Food Law, whereupon the manufacturer submitted the sample P. 48, which was affected by the same destiny, since the aldehyde content with 0.1 allowed only an addition of 0.6% real Jamaika rums. Incidentally, the aldehyde and ester content was in striking disproportion, which suggested the use of an extraordinarily aromatic Jamaika rum.

The complaint continued by the manufacturer, who did not want to believe that it was possible to judge rum products so sharply, finally led to the taking of a control sample of the used genuine rum of the following composition:
Volatile acid 173.4
Ester 1530.3
Aldehyde 23.5

Thus, both the suppositions on the part of the Jamaika rum used in this case and the fact that the Rumverschnitt sample P. 48 could actually contain no more than 0.5% real Jamaika rum and was properly complained of under § 10 of the Food Act.

If one does not want to start from the absolute average of the Lusson-Girard numbers to Williams when assessing and calculating Jamaika rum products but distinguishing the conscious 2 quality series from the outset, one has the quality average values for the above-mentioned absolute average number of 771.3 and 545.8 respectively to insert 996.9. The result of the calculation then reflects the probable additional amount of Jamaika rum in the form of the Jamaica rumored qualities, which certainly has its amenity.

Kunstrum.

After these presentations about real rum and Rumverschnitte Kunstrum may now find a discussion that is often produced with the aid of Rum essence also using some real rum and in the retail trade only too often with the deceptive name “Rum” or “Rumverschnitt” appears.

In this direction, relatively little work is available

A. Skala (Atti della R. Academia medica di Roma 1890.) placed in a Kunstrum to 100 cc. absolute alcohol 258.0 milligrams of acetic acid ethyl ester in addition to 43.0 formic acid solid.

E. Mohler (Compt. rend. 1891, B. 112, S. 53; Chem. Zeitg. 1891, Rep. S. 13.) examined 1 sample Kunstrum with the following results:
Volatile acid 13.4
Ester 5.8
Aldehyde 5.8
Furfurol 0.5
Higher alcohols 18.0

Both products can easily be recognized as artificial with these numbers in mind, taking into account the present scientific rumor experience, without the event, artificial coloring or the nature of the flavor at tasting needs any support. This applies in particular to the Mohler sample, it should be noted that there is neither a real rum nor a Rumverschnitt, which could show on 5.8 aldehyde only 5.8 esters. But even the Skala sample is immediately recognized as Kunstrum, based on the experience of Sell (Arb. Kaiserl. Gesundh.-Amt 1891, B. 7, S. 210.), which found that in real rum to 26 milligrams of acetic acid ethyl ester barely 1 milligram of formic acid ethyl ester, while in the real sample three times the amount of formic acid is found. With extended investigation, this sample would certainly have betrayed in some other direction as Kunstrum. For example, the rapporteur examined 2 products as “rum” on the market, with the following result:

The sample 10 was immediately recognizable by the striking disproportion of aldehyde to esters as Kunstrum. Support in this direction then allowed the presence of tar dyes as well as the abnormal smell and taste. Sample 9 also showed an undeniable mismatch of aldehyde and esters, which was not so obvious. However, with the help of the abnormal smell and taste as well as the abundant presence of tar dyes, this product could certainly be identified as an artificial form. Perhaps the exact determination of the quantities of formic acid as acid and ethyl ester in this rum 9 would still have been possible, which direction has recently been described by H. Finke (Zeitschr., In the Untersdt., Essen, and Genussm., 1913, B. 25, p .), loading material is given to the hand. Unfortunately, this beautiful work by Finke in the attached tables (as well as that of K. Micko (Zeitschr., For sub-d .. Food and pleasure M 1908, B 16, p 438 and B. 19, p 307.) miss the clarity which is so urgently needed in the interest of our entire science, such as the specialized science of spirits, and in particular of rum, since in this field one can only get along with the most painstakingly compiled results of investigations and have a convincing effective wish that in the future all accurate work in the field just described should always give its results calculated on 100 cc. of absolute alcohol, which must be based in particular on the fact that the scientific basis is not limited to specialists in the fine brandy field Laypersons should be able to grasp who, in case of complaint, may claim for clarification then to identify the relationship of event ascertained formic acid and formic acid ester compared to the total volatile acid and total esters are approximately the following tabular form selected and completed:
Volatile acid     with formic acid:
Ester                   thereby antsester:
aldehyde
Furforol
Higher alcohols

Only with this uniform form of publication can one obtain an absolutely clear basis of assessment, by which science, and in particular food chemistry, is served alone.

In 1908 K. Micko, whose name has just been mentioned, drew attention to a completely different distinction between Kunstrum and Rum after discovering a characteristic rumor in the Jamaika rum through a fractional distillation process, namely in the 5th and 6th fractions, who, according to his experiments, counts among the essential oils. This work was followed in 1910 by another (Zeitschr. f. Unters. d. Nahrungs. u. Genussm. 1910, B. 19, S. 305.), for which this researcher 5 samples of real Jamaika rum of the company Segnitz & Co., Bremen, a sample conc. Jamaika rum of the “Jamaikarumcompany” in Amsterdam, as well as 3 samples of real Cubarum, as well as each 2 samples genuine Demerara rum and real Batavia Arrak on its typical Rum frangrance had examined, d. H. 11 samples of sugar cane and 2 samples of rice distillates. The result of the investigation was, in Micko’s own words, such that:

a) in the case of the 3 samples Cuba rum (according to p. 308, para. 4) “the fragrance of the 5th and 6th fractions was reminiscent of Jamaika rum, but did not stand out clearly”;
b) in the 2 samples Demerara rum (according to p. 309, para. 2) “in the 5th, 6th and 7th fractions a smell similar to the typical fragrance of the Jamaica rum but not distinctly pronounced”;
c) in the case of the six samples Jamaika rum (according to p. 310, par. 3) “in all samples the typical fragrance, as it primarily characterizes the Jamaica rum, could be very clearly detected”;
d) in the 2 samples Batavia-Arrak (according to p. 313, para. 7) “the smell of the typical fragrance of Jamaicarum was also clearly perceptible”.

Despite these clear results, Micko sticks to it:
1. “that its typical rum fragrance arose during the fermentation, because in the sugar cane certain bodies are contained, which supply during the fermentation that wonderful perfume”, and
2. that this fragrance was made to distinguish rum.

Unfortunately, both are wrong! For if the Micko’s Jamaika rum fragrance had originated by the sugar cane fermentation and passed over in the distillation, it would have to appear undiminished in all real rum products so also the Cuba- and Demerara rum, and should not on the other hand in rice distillates d. H. Batavia-arrak. However, its odoriferous substance undoubtedly has nothing to do with the actual production of rum by distillation, but rather depends either on a deviating treatment of the distillate in certain parts of the country or, finally, only on the last form of shaping. H. combined with the graining and dyeing, which is certainly treated as a factory secret and therefore also in the distilleries themselves in Jamaica may be different. This view is also imposed by the purely practical consideration that the rum comes to us in a strength of about 75 vol.% And must be distilled so high percent, in any case, if you do not also want to accept a backward dilution with water. Of course, under such distillation conditions, all the constituents of the sugarcane fermentation remain, which go so heavily that they are mixed with 30 cc of water during the test procedures of Micko (where 200 cc of Jamaica rum are mixed with alcohol up to 40% by volume) Subjected to distillation and collected in 8 individual fractions of 25 cc each) only in fractions 5 and 6 which are already excessively diluted.

That then such a fragrance, which originates from the substrate, which according to experience is also arbitrarily chosen in the case of cognac, can serve to distinguish between artifacts, may be admitted in many cases; As a rule, however, the variety of its products and the diversity of its products will lead to so many errors that it is even less possible to speak of an infallible distinction, since the survey of the art excludes not only the absence of Jamaica literature but of all literature must be achievable, as it can only be achieved with the most accurate chemical investigation in conjunction with a purposeful degustation.

K. Micko and, together with him, G. Kapeller and Schulze (Pharm. Centralballe 1910 B. 51, S. 165-170.), who have verified that rum process, are, after all, on a questionable judicial refusal, since they assume that a flavoring is the unmistakable main feature of the authenticity of a rum product. which is connected with the sowing and coloring of the rum and therefore as often deviant and as a whole is to be presented as incidental. At the same beginning in the cognac assessment I come back elsewhere.

Hopefully, these overall observations will help to make the old-fashioned, and with much effort created by the best food chemists, chemical appraisal bases in the Roman region a fairer tribute and appreciative acknowledgment. In combination with a practical degustation, they offer the opportunity to be able to correctly and sharply evaluate all kinds of rum products. There is really no need to resort to procedures which, since they do not go to the heart of the matter, become obsolete at all times and can never provide complete security at all.

Fincke E. About the distinction between Jamaikarum and Kunstrum. 1913

Sponsor my distilling work simply by sharing the artisan workshop of the Bostonapothecary on social media. Copy, Paste, Support!

Fincke E. Über die Unterscheidung von Jamaikarum und Kunstrum, Z. Unters. Nahr. Genussm. 25 (1913), p. 589-596.
About the distinction between Jamaikarum and Kunstrum
[link to the original German]

This paper is no block buster but it does give a glimpse of scientific advancement in tackling first the puzzle of fraud and then eventually using the same tools for advancement in the distillery. Some of the techniques in here would become quickly outdated such as measuring free volatile acidity as formic instead of acetic. Eventually around the work, techniques of analysis would refereed and collectively improved. Personally, I’m trying to locate the origins of a few of the techniques I want to champion. So far it looks like Karl Micko invented them before they were perfected by Arroyo. Keep in mind the rums in here are original rum which is a concentrate. Then a stretched version of that which is diluted with local German spirits then adulterated rum and a version of adulterated rum that has a percentage of original rum.

About the distinction between Jamaikarum and Kunstrum.
(Fifth communication of contributions on the determination of formic acid in foodstuffs.)
From
Heinrich Fincke.
Communication from the Food Inspectorate of the City of Cologne
(Director: Dr. Große-Bohle.)
(Received on 14, March 1913.)

That rum contains free formic acid and formic acid esters is known, as well as that the artificial rum essences contain formic acid esters. It seemed doubtful to me that the formic acid content of rum on the one hand and Kunstrum on the other hand fluctuated within the same values. I therefore made determinations of free and ester-bound formic acid in a number of samples of rum, rum blends, Kunstrum, and rumessenz. In order to exclude disturbances of the formic acid determination by aldehydes and other non-acidic components, steam distillation by calcium carbonate alluvium was used. Further, sodium chloride was added to the solution to be heated with mercuric chloride, as in this way, as already reported (Diese Zeitschrift 1913, 25, 386), a purer mercuric chloride is obtained. The investigation showed that the formic acid determination in many cases with success to the distinction of Rum bezw. Rumverschnitt and Kunstrum can be used. In the context of other results of the study, this will be reported below.

The study covered the content of fragrance, tar dye, alcohol, esters, free and ester formic acid.

The volatile acid was also initially determined in a part of the samples according to the suggestion of Micko (Diese Zeitschrift 1908, 16, 437.). However, it has been shown that the method not only gives no real but also no comparable values, since the amount of volatile acid passing in a certain amount of distillate is also dependent on the alcohol content by high alcohol content (i.e. original rum samples) passes relatively less acid as in low-alcohol blends. For a reasonably correct determination of the volatile acidity in rum, it will be necessary to do the same with wine. Attempts were not made.

The test for perfume was done by Micko (Diese Zeitschrift 1908, 16, 440 und 1910, 19, 310). The odor test of the individual fractions obtained in the distillation proved to be a valuable means of rum judgment. In order to obtain the fragrances always approximately in the same fraction, it seems to me appropriate to dilute samples with higher alcohol content by means of water up to about 30 Vol. % alcohol.

For the determination of the alcohol, 25 cc of the sample were diluted with 35 cc of water and subjected to distillation; In a 50 cc pycnometer about 45 cc distillate was collected and treated in a known manner on.

The determination of the ester content was combined with the determination of formic acid. For this I proceeded as follows: 100 cc of original and artificial stone were mixed with 1 g of sodium acetate in 200 cc of the sample in a flask of about 600 cc in diameter, fitted with a double-perforated stopper, steam inlet tube and distillation head and connected to a steam generator. This additive was intended to prevent as far as possible the transition of free formic acid during distilling off the esters. The distillation head was connected to a Liebig’s condenser of at least 50 cm shell length. Passing a slight stream of steam, 125 cc were distilled off-when 200 cc of the sample had been applied-200 cc distilled off. The heating of the flask was conducted so that the volume of liquid was reduced to about 50 cc.

The distillate was initially set aside for the determination of esters and ester formic acid.

Between the distillation head and Liebig’s condenser, a long-necked flask equipped with Stoltzenberg’s steam inlet tube was then connected, which was charged with a precoat of 2 g of calcium carbonate in about 100 cc of water. The liquid in the first flask was acidified by the addition of 2 g of tartaric acid. With vigorous steam flow I produced 750 cc of distillate and kept the liquid volume in the flask evenly to 50 cc. The filtrate of the calcium carbonate alluvium was acidified with a few drops of dilute hydrochloric acid and heated in the usual way with sodium acetate, sodium chloride and mercuric chloride. The value determined from the weighed mercury chloride indicates the amount of free formic acid.

The first distillate containing the esters was neutralized and allowed to stand with a measured excess amount of 1/10 or 1/4 N sodium hydroxide solution for 24 hours at ordinary temperature. Back titration gave me the amount of alkali used to saponify the esters. If back titration showed that only a slight excess of alkali was present, that is, that the amount of alkali used had possibly been insufficient, a measured amount of liquor was again added and the residue was titrated back after a further 24 hours.

The resulting neutral liquid was concentrated in the water bath to about 30 to 40 cc and subjected to addition of excess phosphoric acid in the same apparatus and in the same manner as in the determination of the free formic acid of the steam distillation by a calcium carbonate alluvium. The filtrate of the latter was also treated as indicated there. The value obtained indicates the content of ester-formic acid.

The results are set forth in Table p. 594 and 595. In addition to the aforementioned provisions, a number of calculated values are listed here.

In order to be able to conveniently compare the values for esters, free and bound formic acid with each other and with other values, their amounts are stated, except in the amount by weight, in tenths of milligram equivalents = cc of 1/10 N. lye.

The sum of free and ester formic acid is calculated as total formic acid.

The tenths of milligram equivalent values for ester, free, ester, and total formic acid have been calculated to be 100 g of alcohol, since this eliminates the influence of the variability of alcohol.

It is also determined how many parts of ester formic acid and total formic acid (in equivalents) are present per 100 equivalents of total ester.

Endlich ist dieses Verhältnis der Gesamt-Ameisensäure zur Estermenge berechnet worden, nachdem von der in 100 ccm der Probe enthaltenen Gesamt-Ameisensäure 0.5 1/10-mg-Äquivalent (= etwa 2 mg Ameisensäure) in Abzug gebracht sind. Der Grund dieser Berechnung wird im nachfolgenden erklärt werden.

In a rum sample that is not unchanged orginalrum, there are the following options:

1. Original rum is adjusted to drinking strength by adding water. Here, the alcohol content and all other values are evenly reduced, but their quantitative ratio remains unchanged. The strength of the dilution results from the alcohol content.

2. Original rum is stretched with alcohol of the same strength. In this case, the alcohol content remains unchanged, however, the alcohol-related values of the other ingredients are depressed. The strength of the elongation results from the values calculated for alcohol for ester and free and ester-shaped. Formic acid.

3. Original rum is stretched with water and alcohol at the same time This case is in the production of ready to drink Rumverschnittes ago. Both the values for alkohol and all other constituents are reduced, but to varying degrees. The dilution with water results from the alcohol content, the dilution with alcohol from the values calculated for 100 g alcohol for ester and formic acid.

4. The product has received an addition of artificial rum essence. There may have been an addition of rum or have been omitted. If rum has been used, then at the same time a strong stretching with water and alcohol took place, otherwise the addition of ester would be pointless. Depending on how rum is used or not, and depending on the composition of the rum essence, very different values will be obtained.

With the specified provisions, one will generally come to a safe judgment even in these cases. If there is no typical Rum aroma, so Kunstrum is of course. If rum aroma is detected, the amount of ester must be reasonably consistent with the strength of the perfume; high ester value with low perfume content indicates the addition of artificial esters.

The Rum aroma is still in strong dilution, usually even in a dilution of the original Jamaican rum 1: 100 perceptible. The Rumverschnitte usual in the trade contain at present usually not (at least not substantially) over 5 to 7% of original Rum. The ester content of a Rumverschnittes is accordingly low. Since the alcoholic strength of the original rum is about twice that of the rum blended, the percentage of alcohol originating from the original rum is greater by the same amount.

If there are doubts as to whether the perfume content of a rum sample is sufficient in comparison to the ester content, dilute the sample with 30% alcohol to such an extent that the amount of ester contained in 100 cc is equal to about 1 cc 1/10 N. lye. According to my experience so far, the fragrance in the fractional distillation is still clearly perceptible.

If the composition of the artificial rum esters deviates from that of the natural rum esters, as is usually the case, this must be expressed in the results of the investigation. To determine a difference in the composition of the esters is primarily the formic acid determination, because the formic acid can be determined even in small quantities with reasonable accuracy, and because it is an integral part of the Rum aromas. Also, the formic acid content of the artificial rum essences is usually considerably larger than that of the natural Rum ester, if it refers to the total amount of ester in both cases.

Here, however, a difficulty must be considered. When investigating rum samples that were reliable and that were otherwise perfect in the test results, slightly larger amounts of free formic acid were found than expected from the study of the related original rum samples. In one case about 0.35 mg was expected, in the other case 0.65 mg of free formic acid in 100 cc; instead, 1.71 mg, found 1.03 mg, respectively. The increase may be due, at least in part, to unavoidable decomposition of the sugar in the distillation, but the surplus value obtained in the first case was too high to make this assumption appear sufficient. The explanation was found in that the formic acid found was partly derived from caramel, which was used for dyeing and usually contains small amounts of formic acid. In several caramel solutions, so-called Zuckercouleur, which were subsequently examined, the following amounts of formic acid were found in 100 cc: 1st trace, 2. 0.058%, 3. 0.219%.

Thus, too high values can be found in the determination of free formic acid for two reasons. On the other hand, the values obtained for the esteric formic acid are flawless, since neither the sugar color nor the sugar decomposition can be considered here. The values found for formic acid in ester form can only be determined by the original rum or by artificial rum esters.

After various experiments it seems impossible that the excess that can be found in the determination of free formic acid will exceed 2 mg for 100 cc. This value respectively for 0.5 cc 1/10 N. lye is therefore to be subtracted from the amount of free or total formic acid in rum blends, real and alleged, when calculating their ratio to the amount of ester. This has happened in the last column of numbers in the table; the penultimate column shows the values ​​without correction. Also, when comparing the free formic acid with other values ​​one will have to consider how much their real value may possibly be lower. The fact that the proposed correction is more than sufficient indicates that the levels of free formic acid found in the Ruin Blends under investigation, in which the rum from the original rum is included, do not reach the level of correction. In addition, in many cases tar dye and no sugar color is used for coloring. As a result, the ester related corrected ratios, which would actually have to be in the same amount as the original rum – between 2.0 and 6.4 – do not have any positive values ​​for the rum blends listed.

Looking at the results of the examination of the original rum samples, the following results are obtained: Fragrance was always high, tar dye was never present. The alcohol content varied between 55.9 and 61.6 g in 100 cc, the amount of ester between 30.0 and 87.2 1/10-mg equivalents for 100 cc. The content of free and ester of formic acid was quite similar for all samples. In 100 cc, I found 3.28 to 5.03 mg of free formic acid respectively 0.71 to 1.09 1/10-mg equivalents, of ester-formic acid 3.34 to 4.45 mg or 0.73 to 0.97 1/10-mg equivalents. There were 50 to 144 1/10-mg equivalents of ester, 1.2 to 1.9 1/10 mg equivalents of free formic acid and 1.2 to 1.6 1/10-mg equivalents of bound formic acid per 100 g of alcohol. 2.0 to 6.4 parts of total formic acid were calculated on 100 parts of ester.

The Rumverschnitte all showed the typical perfume. In part, they were dyed with tar dye. Values ​​for esters were low, ranging from 0.75 to 2.4 1/10 mg equivalents apart from the home-made blend (No.9 of the Table), which showed a higher value – 4.6 1/10-mg equivalents , However, part of the samples (Nos. 7 and 8) were made from the two ester-poorest of the original rum samples listed. The values ​​for free formic acid increased to 1.03 mg in tar-color-stained rum blends, and to 1.71 mg in 100 cc for those caramel-stained. It has already been stated that a correction should be made here. In the calculation of the alcohol content, the error is less important because the alcohol content is considerably greater; in the calculation of the usually very low ester content, it appears essentially as the penultimate column of numbers in the table shows. The mixture I produced (No. 9) had no added extractives and caramel; Here, therefore, I found only the small amount of formic acid, which originated from the original rum, and which theoretically had to be 0.23 mg in 100 cc.

Ester-formic acid was found only in traces in the blends; as such, levels were considered below 0.5 mg; in one case (No. 10) the amount has been weighed. The findings thus coincide with the theoretical requirement.

The Kunstrum samples had in part been marketed under designations that suggested a better product. One of the samples showed Rum aroma clearly. Two more samples appeared to have received very little added rum. They contained 18.5 to 33.1 g of alcohol in 100 cc and with one exception tar dye. The content of esters varied widely between 4.2 and 21.2 1/10-mg equivalents; Accordingly, the ratio of esters to alcohol varied between 13.7 and 87.2. For the majority of Kunstrum samples, the alcohol-related ester content was within the limits of unblended rum; in no case did it sink to the values ​​found in the Rumverschnitten purchased. Apart from the failure of the fragrance sample, in most cases the values ​​found for formic acid, especially the ratio of free and total formic acid to alcohol and the ratio of total formic acid to esters, indicate that artifacts are present. 2.68 to 26.01 mg were found on free formic acid, traces of up to 4.84 mg in 100 cc of ester-formic acid were found. Striking is also the preponderance of free formic acid over the ester formic acid; with the original rum, both values ​​are approximately the same. In the case of artificial rum essences, a greater percentage of the esters are in general formic acid esters; above all they contain much free formic acid, since apparently poorly esterified preparations are used. The investigation of two ruin counts confirmed this.

In many cases, a proper assessment of rum without the determination of free and bound formic acid will be possible. That these provisions can sometimes serve well, however, is shown above all by sample no. 14. In the presence of rum and artificial rum, the presence of formic acid makes the assessment very easy. In the dependence of the formic acid content of the respective composition of the artificial Rum essence lies naturally a lack of the procedure – the possibility of the failure.

1) According to the manufacturer, 10% of the alcohol is made from rum alcohol of the original Jamaican rum II.
2) According to the manufacturer, 14% of the alcohol is made from rum alcohol of the original Jamaican rum III.
3) Self-made waste containing 5% of original Jamaican rum IV so that 10% of the alcohol is rum alcohol.

4) The samples no. 13 and 14 are from the same manufacturer, according to which f-Rum “Faconrum” and ff-Rum mean “Fine Faconrum” and according to whose confession the sample no. 13 Kunstrum and the sample no. 14 Kunstrum with Rumzusatz is.
5) In cases in which calculation of the total formic acid was not possible due to the minority of ester-formic acid, maximum values were used in accordance with the method; at the sample no. 18 was based on the lowest value of the calculation.

The number of original rum samples examined in the manner indicated is still small; It is therefore to be expected that in further investigations, somewhat greater fluctuations in the values of free formic acid present in ester form will be found. Therefore, it is desirable that further material in this direction is provided by the professionals.

Operation Rum Babelfish, A bibliography

Sponsor my distilling work simply by sharing the artisan workshop of the Bostonapothecary on social media. Copy, Paste, Support!

Operation Rum Babel Fish is a project to collect, translate, unify, annotate, and link all the world’s great papers on rum technology.

Authors will use the papers to dazzle us with new tellings of spirit histories. The marketing departments of old producers will open up a little more as history gets filled in and we’re all less inclined to swallow shit. New producers will emerge informed and energized by their predecessors, so we’ll no doubt see new fine rums.

What we’re finding is that rum is especially well studied, more so than any other spirit category, and has always been incredibly progressive. One scientist, exploring Batavia Arrak (discovered in this bibliography), went on to win a Nobel. We can also attach first names to so many ideas and see that rum thinkers back then were probably better connected and more familiar with each other’s works than we are today.

Below in two parts are excerpts of a bibliography created by sugar technologist, Hubert Von Olbrich, for the 1975 rum symposium. The original bibliography has entries in English, Spanish, French, and German. For this post, I tossed out the English entries and the Spanish entries I’ve already covered (such as Arroyo). I then took the French and the German and translated the titles. The second complete part is at the bottom of this document and may inform someone who is curious what I narrowed down from. The first part, separated by a line break, are citations I singled out as the most promising. I either linked to the originals which need translated or added annotations to help locate the others. Some are challenging and will require some serious library sleuthing.

One citation already proved worth all the work and was even found already translated. This work, by the Nobel prize winning scientist describes Batavaia arrak as a Schizosaccharomyces Pombe rum that has a symbiotic fermentation from the added rice and describes the process. This is very different than previously understood and points to our hero Pombe yet again. What else will we find?

Nicola Gref already helped reveal some extra juicy bits by annotating the Olbrich’s chapter in German from his 1970’s History of Molasses. Stephan Berg from the Bitter Truth is working on the 1936 German language document Olbrich singled out as extra important.

We can have a lot of confidence in Olbrich’s bibliography, but we already know he didn’t find everything. He was however German, and besides a technologist, he was also a historian and bibliophile. Therefore, Olbrich is our best shot at knowing what has been published in the German language that has been hard to reach.

Laying eyes on juicy historical information for the very first time is incredibly rewarding. If you want to get in on the game and help reveal important bits of spirits history, feel free to track down some of the citations and translate them. Comment on anything you’re working on.

Right now I’m working on all 30 years of French papers from the INRA. Next up I’m going to tackle all the citations from the Rum Pilot Plant that pertain to rum aroma (I have their annotated bibliography). Then I’ll dig back into what ever is left here. The BPL is also about to send me the 150 pages of papers presented at the 1975 rum symposium, many of which will need translated.

To quote Olbrich before we commence:

It is an irrefutable fact that a library is cheaper than a laboratory and that inquiries are far less costly than investments in development work which is already being carried out elsewhere. By means of thorough information regarding the basic position of science and technique, irrational brain-work is avoided, fruitless researching and inventing activities are prevented and the squandering of economic power and capital is hindered. With other words: Ascertainment of which results and suggestions have already been published in order to solve a problem, serves the rationalization and increase in the productivity of science and practice. Unproductive searching, idle effort and erroneous investments are thus avoided.

Andres M. Notes sur l’évolution des installations de production des rhums. Industries alimentaires et agricoles. Juillet-aoüt (1970), p. 901-906.
Notes on the evolution of rums production facilities. July-August
[This is an easy ILL]

Anonymous. Distillation des mélasses pour la fabrication des tafias et des rhums, Sucrerie Indigène 6, (1871/72) p. 486-491.
Distillation of molasses for making tafias and rums
[original French. This actually looks worth translating and has some great illustrations.]

Anonymous. Rum production in Madeira. Facts about Sugar 14 (1922), p. 401.
[The article turned out to be a snippet about reducing produce size so the link above is an image of it.]

Anonymous. Die Fabrikation des Jamika-Rums und des Batavia-Arraks (Ein Überblick über die wichtigsten Originalarbeiten, besonders englischer und holländischer Forscher). Deutsche Destillateur-Zeitung 57 (1936), n0. 29, p. 114, no 3o, p. 123-124, no 35, p. 145-146, no 38, p. 159, no 43/44, p. 182-183, no 5o, p. 205-206 (with 27 literature references).
The Fabrication of Jamaica Rum and Batavia Arraks (A Review of the Most Important Original Works, Especially English and Dutch Researchers)

Anonymous. Aussichten auf die Rumherstellung aus Zuckerrohr in Spanien, Prager Zuckermarkt. p. 31, supplement to Z. Zuckind. CSR 66 (3) (1942/43).
Outlook on rum production from sugarcane in Spain

Boes J. Über das Vorkommen von Aminen in Arrak und Rum. Apoth. Ztg. 22 (1907), p. 56.
About the occurrence of amines in arrak and rum
[Apotheker Zeitung link to entire issue scanning] [image of the short article page] [higher up link to use as a resource]

Bonis A. Untersuchungen über die Zusammensetzung der Rume von Martinique, Oesterr. Ung. Z. Zuckerind. Landw. NF 39 (1910), p. 6oo.
Studies on the composition of the rums of Martinique [Österreichisch-Ungarische Zeitschrift für Zuckerindustrie und Landwirtschaft]

Brauer K. Deutscher Rum, Chem. Ztg. 46 (1922), p. 161-163, 185-186; Z. Ver. Zucker-ind. 73 (1923), p. 332-333; Deutscher Arrak, Chem. Ztg. 47 (1923), p. 365-367.
German rum / German Arrak [Chemiker-Zeitung]

Comite consultatif durhum. Rapport du groupe d’experts sur les problèmes posés par l’intégration du rhum dans le Marché Commun, C. C. R., juillet 197o, 45 p. ronéotées, annexes.
Report of the group of experts on the problems posed by the integration of rum into the Common Market

Eijkman C. Mikrobiologisches über Arrakfabrikation in Batavia, Zbl. Bakteriol. Parasitenkunde, 1. Abt., 16 (1894), p. 97-103.
Microbiological about Arrak fabrication in Batavia
[This is a wildly important paper and the above link is to it translated and explained.]

Ficker M., Szus S. Über Rumgärung, Zent. Bakt. Parasit. 82 (1930), p. 199-214.
About rum fermentation [Zentralblatt für Bakteriologie, Parasitenkunde]

Fincke E. Über die Unterscheidung von Jamaikarum und Kunstrum, Z. Unters. Nahr. Genussm. 25 (1913), p. 589-596.
About the distinction between Jamaikarum and Kunstrum
[My translation]

Guillaume J. Untersuchungen über das Rum-Aroma, Bull. Assoc. Chimistes 58 (1941), p. 163-174; Ztschr. Wirtschaftsgr. Zuckerind. 93 (1943), p. 50-52.
Studies on the rum flavor

Haeseler G. Neuere Arbeiten über Rumfabrikation, Branntweinwirt Schaft 3 (1949), p. 180-181.
Recent work on rum production

2. Saito K. Notiz über die Melasserumgärung auf den Bonininseln, Österreichisch-Ungarische Zeitschrift für Zuckerindustrie und Landwirschaft 37 (1908), p. 918.
Note about the molasses fermentation on the Bonin Islands, Austro-Hungarian magazine for sugar industry and agriculture
[The above link is my translation. This article is important because it acknowledges a film yeast rum.]

3. Bonis A. Untersuchungen über die Zusammensetzung der Rume von Martinique, Österreichisch-Ungarische Zeitschrift für Zuckerindustrie und Landwirtschaft 39 (1910), p. 600.
Studies on the composition of Martinique’s rums, Austro-Hungarian magazine for sugar industry and agriculture

4. Simon A. Untersuchungen über die Einteilung der Rume von Martinique nach ihrem Verunreinigungskoeffizienten, Osterreichisch-Ungarische Zeitschrift für Zuckerindustrie und Landwirtschaft 39 (1910), p. 600-601.
Investigations on the classification of the areas of Martinique according to their impurity coefficient, Austrian-Hungarian magazine for sugar industry and agriculture

5. Brauer K. Deutscher Arrak (Chemiker-Zeitung no 51/52, 1923) ), Zeitschrift des Vereins der Deutschen Zucker-Industrie 73 (NF. 60) (1923), P. 332-333.
German Arrak-Journal of the Association of the German Sugar Industry

6. Winkelhausen W. Verfahren zur Vorbereitung von Zuckerlösungen beliebiger Herkunft zur Herstellung einer Maische für Rum- oder Arrakdestillate, DRP no 106 654; Deutsche Zuckerindustrie 67 (1942), p. 47.
Process for preparing sugar solutions of any origin for making a mash for rum or arrak-distillates

3. V[on] S. Rum aus Jamaika. Wasser aus Schottland, Branntweinwirtschaft 78 (1956), no 3, p. 51-52.
Rum from Jamaica. Water from Scotland

4. anonymous. Bundesrepublik grösster Rum-Mark der Welt, Branntweinwirtschaft 105 (1965), no 7, p. 174.
Federal Republic of the world’s largest Rum-Market

Jayatunge N., Fernando QU. Änderungen in der chemischen Zusammensetzung des Arraks während der Reifung. Euclides (Madrid) II (1951), P. 404-406 ; rev. : Chem. Zbl. (1954) II, 5872.
Changes in the chemical composition of the arraks during maturation

Jonscher A. Zur Kenntnis und Beurteilung von Rum, Rumverschnittenund Kunstrum, Z. Öffentl. Chem. 20 (1914), p. 329-336, 345-349.
For the knowledge and evaluation of rum, Rumverschnitten and Kunstrum
[untranslated German] [my translation]

Lebbin. Ein neuer Weg zur Beurteilung von Rum und Arrak. Chem. Ztg. 50 (1926), p. 334.
A new way to judge rum and Arrak [Chemisches Zentralblatt]

Luckow C. Was verstehe man unter der « Esterzahl » beim Original-Rum, Mitt. ATL 2o (1930), no 1, p. 28-29, 31 (1941), no 2, p. 5.
What is meant by the “ester number” of the original rum?

Luckow C. Über die Begutachtung von Rum, Arrak und Kirschwasser mit Hilfe der Ausgiebigkeitsprobe, Brennerei-Ztg. 50 (1933), 86-87.
On the evaluation of rum, arrack and kirsch with the help of the exhaustive test
[this should be easily ILL requestable]

OLBRICH H. Über die Arrak-Gewinnung aus Rohrmelasse, DestillateurLehrling II (1961), p. 57-62 (Supplement to Branntweinwirtschaft) ; rev. : Z. Zuckerind. 13 (1963), p. 236.
About the arrack extraction from molasses

Rose L. Die Alkohol- und Rumfabrikation in Costa Rica, Z. Spiritusind. 51 (1928), p. 194-195.
The alcohol and rum production in Costa Rica

Schaffer E. Geruchsprüfung von Rum, Chem. Ztg. 44 (1923), p. 934.
Odor test of rum [Chemiker-Zeitung (this should be ILL gettable)]

Simon A. Untersuchungen über die Einteilung der Rume von Martinique nach ihrem Verunreinigungskoeffizienten, Oesterr. Ung. Z. Zuckerind. Landw. NF 39 (1910), p. 600-601.
Studies on the classification of Martinique’s rums according to their contamination coefficient

WALTER E. Die Grogprobe, ein Hilfsmittel zur Beurteilung von Rum und Arrak, Alkohol-Industrie (1953), no 7, P. 165.
The grog sample, a tool for evaluating rum and arrack

Wollny G. Martinique-Rum [aus Zuckerrohrsaft und/oder Rohrmelasse], Alkohol-Industrie 77 (1964), no 2, p. 47-49.
Martinique rum from sugar cane juice and / or molasses

Wrede F. Die Rumbrennerei in Übersee und in Deutschland, Z. Spiritusind. 51 (1928), p. 150.
The Rum distilleries overseas and in Germany

Wüstenfeld H., Luckow C. Zur Frage der Begutachtung von Auslandsrum und Arrak, Korrespondenz ATL (Abteilung Trinkbranntwein und Likörfabrikation im Institut für Gärungsgewerbe Berlin) 18 (1928), p. 23-25.
On the question of the assessment of foreign rum and Arrak

Wüstenfeld H. Luckow C. Esterzahl, Ausgiebigkeit und Qualitat von rum und Arrak sorten des Handels, Mitt. der ATL 20 (1930), no 1, p. 2-6.
Ester number, abundance and quality of rum and arrak types of trade
[here is something (page 129) these two did together on vacuum distillation of beverage stuff. It looks like Curt Luckow wrote lots of abstract for this journal and may have been a major German thinker.]


Andres M. Notes sur l’évolution des installations de production des rhums. Industries alimentaires et agricoles. Juillet-aoüt (1970), p. 901-906.
Notes on the evolution of rums production facilities. July-August

Anonymous. Distillation des mélasses pour la fabrication des tafias et des rhums, Sucrerie Indigène 6, (1871/72) p. 486-491.
Distillation of molasses for making tafias and rums

Aanonymous. Rum production in Madeira. Facts about Sugar 14 (1922), p. 401.

Anonymous. Die Fabrikation des Jamika-Rums und des Batavia-Arraks (Ein Überblick über die wichtigsten Originalarbeiten, besonders englischer und holländischer Forscher). Deutsche Destillateur-Zeitung 57 (1936), n0. 29, p. 114, no 3o, p. 123-124, no 35, p. 145-146, no 38, p. 159, no 43/44, p. 182-183, no 5o, p. 205-206 (with 27 literature references).
The Fabrication of Jamaica Rum and Batavia Arraks (A Review of the Most Important Original Works, Especially English and Dutch Researchers)

Anonymous. Aussichten auf die Rumherstellung aus Zuckerrohr in Spanien, Prager Zuckermarkt. p. 31, supplement to Z. Zuckind. CSR 66 (3) (1942/43).
Outlook on rum production from sugarcane in Spain

Boes J. Über das Vorkommen von Aminen in Arrak und Rum. Apoth. Ztg. 22 (1907), p. 56.
About the occurrence of amines in arrak and rum

Bonis A. Untersuchungen über die Zusammensetzung der Rume von Martinique, Oesterr. Ung. Z. Zuckerind. Landw. NF 39 (1910), p. 6oo.
Studies on the composition of the rums of Martinique

Brauer K. Deutscher Rum, Chem. Ztg. 46 (1922), p. 161-163, 185-186; Z. Ver. Zucker-ind. 73 (1923), p. 332-333; Deutscher Arrak, Chem. Ztg. 47 (1923), p. 365-367.
German rum / German Arrak

Comite consultatif durhum. Rapport du groupe d’experts sur les problèmes posés par l’intégration du rhum dans le Marché Commun, C. C. R., juillet 197o, 45 p. ronéotées, annexes.
Report of the group of experts on the problems posed by the integration of rum into the Common Market

Eijkman C. Mikrobiologisches über Arrakfabrikation in Batavia, Zbl. Bakteriol. Parasitenkunde, 1. Abt., 16 (1894), p. 97-103.
Microbiological about Arrak fabrication in Batavia

Ficker M., Szus S. Über Rumgärung, Zent. Bakt. Parasit. 82 (1930), p. 199-214.
About rum fermentation

Fincke E. Über die Unterscheidung von Jamaikarum und Kunstrum, Z. Unters. Nahr. Genussm. 25 (1913), p. 589-596.
About the distinction between Jamaikarum and Kunstrum

Guillaume J. Untersuchungen über das Rum-Aroma, Bull. Assoc. Chimistes 58 (1941), p. 163-174; Ztschr. Wirtschaftsgr. Zuckerind. 93 (1943), p. 50-52.
Studies on the rum flavor

Haeseler G. Neuere Arbeiten über Rumfabrikation, Branntweinwirt Schaft 3 (1949), p. 180-181.
Recent work on rum production

2. Saito K. Notiz über die Melasserumgärung auf den Bonininseln, Österreichisch-Ungarische Zeitschrift für Zuckerindustrie und Landwirschaft 37 (1908), p. 918.
Note about the molasses fermentation on the Bonin Islands, Austro-Hungarian magazine for sugar industry and agriculture

3. Bonis A. Untersuchungen über die Zusammensetzung der Rume von Martinique, Österreichisch-Ungarische Zeitschrift für Zuckerindustrie und Landwirtschaft 39 (1910), p. 600.
Studies on the composition of Martinique’s rums, Austro-Hungarian magazine for sugar industry and agriculture

4. Simon A. Untersuchungen über die Einteilung der Rume von Martinique nach ihrem Verunreinigungskoeffizienten, Osterreichisch-Ungarische Zeitschrift für Zuckerindustrie und Landwirtschaft 39 (1910), p. 600-601.
Investigations on the classification of the areas of Martinique according to their impurity coefficient, Austrian-Hungarian magazine for sugar industry and agriculture

5. Brauer K. Deutscher Arrak (Chemiker-Zeitung no 51/52, 1923) ), Zeitschrift des Vereins der Deutschen Zucker-Industrie 73 (NF. 60) (1923), P. 332-333.
German Arrak-Journal of the Association of the German Sugar Industry

6. Winkelhausen W. Verfahren zur Vorbereitung von Zuckerlösungen beliebiger Herkunft zur Herstellung einer Maische für Rum- oder Arrakdestillate, DRP no 106 654; Deutsche Zuckerindustrie 67 (1942), p. 47.
Process for preparing sugar solutions of any origin for making a mash for rum or arrak-distillates

3. V[on] S. Rum aus Jamaika. Wasser aus Schottland, Branntweinwirtschaft 78 (1956), no 3, p. 51-52.
Rum from Jamaica. Water from Scotland

4. anonymous. Bundesrepublik grösster Rum-Mark der Welt, Branntweinwirtschaft 105 (1965), no 7, p. 174.
Federal Republic of the world’s largest Rum-Market

Jayatunge N., Fernando QU. Änderungen in der chemischen Zusammensetzung des Arraks während der Reifung. Euclides (Madrid) II (1951), P. 404-406 ; rev. : Chem. Zbl. (1954) II, 5872.
Changes in the chemical composition of the arraks during maturation

Jonscher A. Zur Kenntnis und Beurteilung von Rum, Rumverschnittenund Kunstrum, Z. Öffentl. Chem. 20 (1914), p. 329-336, 345-349.
For the knowledge and evaluation of rum, Rumverschnittenund Kunstrum

Lebbin. Ein neuer Weg zur Beurteilung von Rum und Arrak. Chem. Ztg. 5o (1926), p. 334.
A new way to judge rum and Arrak

Luckow C. Was verstehe man unter der « Esterzahl » beim Original-Rum, Mitt. ATL 2o (1930), no 1, p. 28-29, 31 (1941), no 2, p. 5.
What is meant by the “ester number” of the original rum?

Luckow C. Über die Begutachtung von Rum, Arrak und Kirschwasser mit Hilfe der Ausgiebigkeitsprobe, Brennerei-Ztg. 50 (1933), 86-87.
On the evaluation of rum, arrack and kirsch with the help of the exhaustive test

OLBRICH H. Über die Arrak-Gewinnung aus Rohrmelasse, DestillateurLehrling II (1961), p. 57-62 (Supplement to Branntweinwirtschaft) ; rev. : Z. Zuckerind. 13 (1963), p. 236.
About the arrack extraction from molasses

Rose L. Die Alkohol- und Rumfabrikation in Costa Rica, Z. Spiritusind. 51 (1928), p. 194-195.
The alcohol and rum production in Costa Rica

Schaffer E. Geruchsprüfung von Rum, Chem. Ztg. 44 (1923), p. 934.
Odor test of rum

Simon A. Untersuchungen über die Einteilung der Rume von Martinique nach ihrem Verunreinigungskoeffizienten, Oesterr. Ung. Z. Zuckerind. Landw. NF 39 (1910), p. 600-601.
Studies on the classification of Martinique’s rums according to their contamination coefficient

WALTER E. Die Grogprobe, ein Hilfsmittel zur Beurteilung von Rum und Arrak, Alkohol-Industrie (1953), no 7, P. 165.
The grog sample, a tool for evaluating rum and arrack

Wollny G. Martinique-Rum [aus Zuckerrohrsaft und/oder Rohrmelasse], Alkohol-Industrie 77 (1964), no 2, p. 47-49.
Martinique rum from sugar cane juice and / or molasses

Wrede F. Die Rumbrennerei in Übersee und in Deutschland, Z. Spiritusind. 51 (1928), p. 150.
The Rum distilleries overseas and in Germany

Wüstenfeld H., Luckow C. Zur Frage der Begutachtung von Auslandsrum und  Arrak, Korrespondenz ATL (Abteilung Trinkbranntwein und Likörfabrikation im Institut für Gärungsgewerbe Berlin) 18 (1928), p. 23-25.
On the question of the assessment of foreign rum and Arrak

Wüstenfeld H. Luckow C. Esterzahl, Ausgiebigkeit und Qualitat von rum und Arrak sorten des Handels, Mitt. der ATL 20 (1930), no 1, p. 2-6.
Ester number, abundance and quality of rum and arrak types of trade

The list adapted from Olbrich

Andres M. Notes sur l’évolution des installations de production des rhums. Industries alimentaires et agricoles. Juillet-aoüt (1970), p. 901-906.
Notes on the evolution of rums production facilities. July-August

Anonymous. Die Fabrikation des Rums in Indien, Hermbstädts, Bulletin 15 (1813), no 3, p. 268-273.
The fabrication of Indian rums. [probably West Indian]

Anonymous. Distillation des mélasses pour la fabrication des tafias et des rhums, Sucrerie Indigène 6, (1871/72) p. 486-491.
Distillation of molasses for making tafias and rums

Aanonymous. Rum production in Madeira. Facts about Sugar 14 (1922), p. 401.

Anonymous. Die Fabrikation des Jamika-Rums und des Batavia-Arraks (Ein Überblick über die wichtigsten Originalarbeiten, besonders englischer und holländischer Forscher). Deutsche Destillateur-Zeitung 57 (1936), n0. 29, p. 114, no 3o, p. 123-124, no 35, p. 145-146, no 38, p. 159, no 43/44, p. 182-183, no 5o, p. 205-206 (with 27 literature references).
The Fabrication of Jamaica Rum and Batavia Arraks (A Review of the Most Important Original Works, Especially English and Dutch Researchers)

Anonymous. Aussichten auf die Rumherstellung aus Zuckerrohr in Spanien, Prager Zuckermarkt. p. 31, supplement to Z. Zuckind. CSR 66 (3) (1942/43).
Outlook on rum production from sugarcane in Spain

Anonymous. Das Rechnen mit Proofgallonen und Proofgraden, Alkohol Industrie 7o (1957), no 18, p. 423.
Computing with proof gallons and proof grades

Anonymous. Die Historie vom Rum, Pott-Kompass 1967, no 3 and 4; 1968, no 2 and 3 (conglomeration).
The history of rum.

Anonymous. Berichte vom Rum-Markt. Kompass 1967, 1968 (conglomeration)
Reports from the rum market

Anonymous. Le rhum. Le Guide de l’Épicier, Avril I968, p. 9-19.
The rum. The Grocer’s Guide

Banc d’essai. Le Rhum. Le nouveau guide Gault et Millau, février 197o, p. 23-27.
The rum. The new Gault and Millau guide

Baraud J., Maurice A., Die höheren Alkohole und die leichten Ester von Rums und Apfelbranntweinen (Les alcools et esters des eaux-de-vie de canne et de pomme). Industrie Alimentaires et Agricoles 80 (1963) 3-7; rev. : Branntweinwirtschaft 103 (1963), 338.
The higher alcohols and the light esters of rums and apple brandies (Les alcools et ales des eaux-de-vie de canne et de pomme)

Bardinet. Bardinet-Négrita, symbole international du rhum français, Bordeaux S. d., 32 p. ill.
Bardinet-Négrita, international symbol of French rum

BLOME R. Englisches America, oder kurtze doch deutliche Beschreibung aller derer denigen Länder und Inseln so der Cron Engeland in Westindien jetziger Zeit zuständig und unterthanig sind: dass sie zeithero von den Franzosen und Englischen des verfluchten Trankes erlernet haben, den man Rum, Rumbullion, oder Ribtdevil, Mortteufel nennet, so noch stärker ist als Weinhefen-Brantwein, und von überbliebener Unreinigkeit des Zuckers und Zuckerrohrs abgezogen und zugerrichtet wird, 1697.
English America, or have a clear description of all these countries and islands, so the Crown England in western India are responsible and subject: that they have learned from time to time the French and English of the cursed potion known as Rum, Rumbullion, or Ribtdevil, Mortteufel, even more so than Weinhefen-Brantwein, is called and stripped of all the uncleanliness of sugar and sugar cane, 1697.

Boes J. Über das Vorkommen von Aminen in Arrak und Rum. Apoth. Ztg. 22 (1907), p. 56.
About the occurrence of amines in arrak and rum

Bonis A. Untersuchungen über die Zusammensetzung der Rume von Martinique, Oesterr. Ung. Z. Zuckerind. Landw. NF 39 (1910), p. 6oo.
Studies on the composition of the rums of Martinique

Brauer K. Deutscher Rum, Chem. Ztg. 46 (1922), p. 161-163, 185-186; Z. Ver. Zucker-ind. 73 (1923), p. 332-333; Deutscher Arrak, Chem. Ztg. 47 (1923), p. 365-367.
German rum / German Arrak

Bremer W. Trinkbranntwein und Likör. 1st Edition 1918; Leipzig : 2nd Edition.
Drinking liquor and liqueur

de Corn. Mode de fabrication du rhum, French Pat. 32956 ; Catalogue 1857, p. 18o.
Method of making rum

CEDAL (Centre de Documentation de l’Alimentation, Paris). Histoire de la canne à sucre et du rhum. Economie Familiale no 22, printemps-été 197o, p . 9-IO .
History of sugar cane and rum

CEDAL (Paris). Richesses françaises d’Outre-Mer, la canne à sucre et le rhum, 1971, 16 p. ; see Z. ZuckInd. 23 (1973) 1, p. 39.
French overseas riches, sugar cane and rum

CEDAL (Paris). Le Rhum. Documentation pratique du CEDAL, 1971, 91 p. with numerous illustrations and tables; see Z. ZuckInd. 23 (1973), p. 39.

Charpentier De Cossigny J. F. Mémoire sur la fabrication des eaux-de-vie de sucre, 1781 (with Supplément, 1782); (an early Mauritian imprint).
Brief on the manufacture of sugar spirits

Commissariat general du plan d’euipment et de la productivite, Réponse au questionnaire de l’intergroupe alcools-boissons alcooliques, VI° plan, avril 1970, 18 p. dactylographiées.
Response to the intergroup alcohol-alcoholic drinks questionnaire

Comite consultatif durhum. Rapport du groupe d’experts sur les problèmes posés par l’intégration du rhum dans le Marché Commun, C. C. R., juillet 197o, 45 p. ronéotées, annexes.
Report of the group of experts on the problems posed by the integration of rum into the Common Market

Comite national Interprofessionnel du rhum. Le rhum, définitions françaises; C. N. I. R., janvier 1965, 64 p.
Rum, French definitions

Cousins H. H. Landwirtschaftliches und Technisches aus der Versuchsstation für Zuckerindustrie in Jamaika, Oesterr. Ung. Z. Zuckerind. Landw., NF 35 (1906), p. 632-634.
Agricultural and Technical from the sugar industry experimental station in Jamaica

Davies J. G. Anwendung von Trockenhefe in Jamaica-Rum-Brennereien, Chem. Abstr. (1952) 9248; Proc. Brit. West Indies Sugar Technol. (1948), p. 23-27; rev. : Branntweinwirtschaft 75 (1953), p. 77.
Use of dry yeast in Jamaican rum distilleries

Direction Des Douanes. Statistiques du commerce extérieur des départements d’Outre-Mer; différents bulletins.
Customs Direction. Foreign Trade Statistics of Overseas Departments

Dormoy Estienne. L’économie sucrière des départements d’Outre-Mer. Institut des Hautes-Études du droit rural et d’Économie Agricole 197o, 25o p. roméotées.
The sugar economy of the overseas departments

Eijkman C. Mikrobiologisches über Arrakfabrikation in Batavia, Zbl. Bakteriol. Parasitenkunde, 1. Abt., 16 (1894), p. 97-103.
Microbiological about Arrak fabrication in Batavia

Federation nationale des producteurs de rhum. Le rhum dans le Marché Commun, décembre 1964, 64 p.
Rum in the Common Market

Fellenberg Th. von. Über den Jamaikarum und seine höheren Alkohole, Mitt. Lebensmittel-Hyg. 1 (1910), p. 352-357.
About the Jamaika rum and its higher alcohols

Ficker M., Szus S. Über Rumgärung, Zent. Bakt. Parasit. 82 (1930), p. 199-214.
About rum fermentation

Fincke E. Über die Unterscheidung von Jamaikarum und Kunstrum, Z. Unters. Nahr. Genussm. 25 (1913), p. 589-596.
About the distinction between Jamaikarum and Kunstrum

Gaber A. Die Fabrikation von Rum, Arrak und Cognac. Leipzig: Hartleben, 1898 (1st Edition); Die Fabrikation von Rum, Arrak, Kognak. 2nd Edition, Wien/Leipzig, 1923.
The fabrication of rum, arrack and cognac

Guillaume J. Untersuchungen über das Rum-Aroma, Bull. Assoc. Chimistes 58 (1941), p. 163-174; Ztschr. Wirtschaftsgr. Zuckerind. 93 (1943), p. 50-52.
Studies on the rum flavor

Haeseler G. Neuere Arbeiten über Rumfabrikation, Branntweinwirt Schaft 3 (1949), p. 180-181.
Recent work on rum production

Harman C. Les Antilles. Collection Life autour du monde. Time-Life, 1969, 157 p. ill.
West Indies. Life collection around the world

Hermbstädt S. F. Die Fabrikation des Rums in Indien, Bulletin des Neuesten und Wissenswürdigsten aus der Naturwissenschaft 15 (1813), no 3, p. 268-273.
The production of rum in India, Bulletin of the newest and most worth knowing from the natural sciences

Herzfeld A. Bericht über die Versuche zur Darstellung Rum-artiger Produkte aus Rübensaft, Melasse und Rohzucker, Zeitschrift des Vereins für die Rübenzucker-Industrie des Deutschen Reiches 27. N. F.; 4o (1890), p. 645-680 ; Oest.-Ung. Z. Zuckerind. Landw. NF 20 (1891), p. 124-128.
Report on the attempts to present rum-like products from beet juice, molasses and raw sugar, Journal of the Association for the beet sugar industry of the German Reich

Institut Für Zuckerindustrie (IZI), Berlin. Compilation of some Rum Papers from the years 1906, 1908, 1910, 1923, 1942. Contents.

1. Cousins H. H. Landwirtschaftliches und Technisches insbesondere über Rumfabrikation aus der Versuchsstation für Zuckerindustrie in Jamaika, Oesterreichisch-Ungarische Zeitschrift für Zuckerindustrie und Landwirtschaft 35 (1906), p. 632-634.
Agricultural and technical in particular on rum production from the experimental station for sugar industry in Jamaica, Austrian-Hungarian magazine for sugar industry and agriculture

2. Saito K. Notiz über die Melasserumgärung auf den Bonininseln, Österreichisch-Ungarische Zeitschrift für Zuckerindustrie und Landwirschaft 37 (1908), p. 918.
Note about the molasses fermentation on the Bonin Islands, Austro-Hungarian magazine for sugar industry and agriculture

3. Bonis A. Untersuchungen über die Zusammensetzung der Rume von Martinique, Österreichisch-Ungarische Zeitschrift für Zuckerindustrie und Landwirtschaft 39 (1910), p. 600.
Studies on the composition of Martinique’s rums, Austro-Hungarian magazine for sugar industry and agriculture

4. Simon A. Untersuchungen über die Einteilung der Rume von Martinique nach ihrem Verunreinigungskoeffizienten, Osterreichisch-Ungarische Zeitschrift für Zuckerindustrie und Landwirtschaft 39 (1910), p. 600-601.
Investigations on the classification of the areas of Martinique according to their impurity coefficient, Austrian-Hungarian magazine for sugar industry and agriculture

5. Brauer K. Deutscher Arrak (Chemiker-Zeitung no 51/52, 1923) ), Zeitschrift des Vereins der Deutschen Zucker-Industrie 73 (NF. 60) (1923), P. 332-333.
German Arrak-Journal of the Association of the German Sugar Industry

6. Winkelhausen W. Verfahren zur Vorbereitung von Zuckerlösungen beliebiger Herkunft zur Herstellung einer Maische für Rum- oder Arrakdestillate, DRP no 106 654; Deutsche Zuckerindustrie 67 (1942), p. 47.
Process for preparing sugar solutions of any origin for making a mash for rum or arrak-distillates

Institut Für Zuckerindustrie, Berlin. Compilation of some Papers about Rum and Rum-Fabrication from the years 1949 till 1967; Contents:

1. [Hae S[eler). Neuere Arbeiten über Rum-fabrikation, Branntweinwirtschaft 3 (1949), no 12, p. 180-181.
Recent work on rum manufacturing

2. Bausch. Rum aus Britisch-Westindien, Branntweinwirtschaft 76 (1954), no 2, p. 27.
Rum from British West Indies

3. V[on] S. Rum aus Jamaika. Wasser aus Schottland, Branntweinwirtschaft 78 (1956), no 3, p. 51-52.
Rum from Jamaica. Water from Scotland

4. anonymous. Bundesrepublik grösster Rum-Mark der Welt, Branntweinwirtschaft 105 (1965), no 7, p. 174.
Federal Republic of the world’s largest Rum-Market

5. Alten Hofen G. Die Wettebewerbssituation auf dem deutschen Rum Markt, Branntweinwirtschaft 1o5 (1965), no 15, p. 407.
The competitive situation on the German rum market

6. Fedders and Dubick. Noch einmal : Die Wettbewerbssituation auf dem deutschen Rum-Markt, Branntweinwirtschaft 1o5 (1965), no 2o, p. 558, 560.
Once again: The competitive situation in the German rum market

7. RATHKE. Bundesmonopolverwaltung für Branntwein zur Einfuhr von Rum, Branntweinwirschaft 1o7 (1967), no 9, p. 219-220.
Federal Monopoly Administration for spirits for the import of rum

Jayatunge N., Fernando QU. Änderungen in der chemischen Zusammensetzung des Arraks während der Reifung. Euclides (Madrid) II (1951), P. 404-406 ; rev. : Chem. Zbl. (1954) II, 5872.
Changes in the chemical composition of the arraks during maturation

Jonscher A. Zur Kenntnis und Beurteilung von Rum, Rumverschnittenund Kunstrum, Z. Öffentl. Chem. 20 (1914), p. 329-336, 345-349.
For the knowledge and evaluation of rum, Rumverschnittenund Kunstrum

Kappeller G., Schulze R. Beitrag zur Rumuntersuchung, Pharm. Ze. tralhalle 51 (1910), p. 165-170.
Contribution to the Rumuntersuchung

Kohut. Kleine Anfrage im Bundestag wegen der Wiederzulassung von Kunstrum und Kunstarrak. Branntweinwirtschaft 100 (1960) 522.
Small request in the Bundestag for the re-admission of Kunstrum and Kunstarrak

Labat P. Nieuwe Reizen naar de Franse Eilanden van America. Amsterdam : B. Lakeman, 1725. Part II (Tweede Deel), 4o4 p.
New Travel to the French Islands of America

Lasserre G. La Guadeloupe. Thèse U.F.I. Bordeaux 1961, 2 tomes

Le Rumeur G. Enchantement des Antilles-Connaissances des îles. Société d’éditions modernes illustrées, 1963, 343 p.
Enchantment of the West Indies-Knowledge of the Islands

Lebbin. Ein neuer Weg zur Beurteilung von Rum und Arrak. Chem. Ztg. 5o (1926), p. 334.
A new way to judge rum and Arrak

Lieber. Rectificateur adapté à un appareil distillatoire pour la fabrication des rhums, Brit. Pat., French Pat. 41 o55 (1858) ; Catalogue 1859, p. 143.
Rectifier adapted to a distillatory apparatus for making rums

Lorck-Schierning. Kleines Rum-Compendium, Alkoholindustrie 64 (1951), 18ვ-185, 221-224.

Luckow C. Was verstehe man unter der « Esterzahl » beim Original-Rum, Mitt. ATL 2o (1930), no 1, p. 28-29, 31 (1941), no 2, p. 5.
What is meant by the “ester number” of the original rum?

Luckow C. Über die Begutachtung von Rum, Arrak und Kirschwasser mit Hilfe der Ausgiebigkeitsprobe, Brennerei-Ztg. 50 (1933), 86-87.
On the evaluation of rum, arrack and kirsch with the help of the exhaustive test

Malignac G. La consommation moyenne d’alcool pur diminue. Economie et statistique, Bulletin de l’INSEE, no 22, avril 1971, p. 49-51.
Average consumption of pure alcohol decreases

Marbeau P. Le régime des alcools d’industrie et des alcools de bouche en France. Librairie Louis Arnette, 1932, 341 p.
The industrial alcohol and beverage alcohol in France

Marillier Ch. Distillerie agricole et industrielle-levurerie, sous-produits. Nouvelle Encyclopédie Agricole J. B. Baillière et Fils 1951, 632 p.
Agricultural and industrial distillery-yeast, by-products

Mariotti F. Rapport du Commerce d’importation et d’exportation des rhums, présenté par F. Mariotti, 12 p. dactylographiées.
Report of the Import and Export Trade of Rums, presented by F. Mariotti

Miot P. Le régime économique de l’alcool, Berger-Levrault 1961, 267 p.
The economic regime of alcohol

Micko K. Über die Untersuchung des Jamaika-und Kunstrums und zur Kenntnis des typischen Riechstoffes des Jamaika-Rums, Z. Unters. Nahr. Genussm. 8 (1908), p. 433-451.
On the study of Jamaica and Kunstrum and the knowledge of the typical fragrance of the Jamaican rum

Micko K. Zur Kenntnis der Untersuchung von Branntweinen (Cuba, Demerara, Jamaikarum, Arrak, Zwetschgenbranntwein, Kognak, Weingelägerbranntwein), Z. Unters. Nahr. Genussm. 19 (1910), p. 305-322.
Noted the investigation of spirits (Cuba, Demerara, Jamaikarum, Arrak, Zwetschgenbranntwein, cognac, Weingelägerbranntwein

Motschmann A. Zusammensetzung von Rum. Korrespondenz-ATL 1915.
Composition of rum

OLBRICH H. Geschichte der Melasse. Berlin 197o, 832 p. ; Chapter : RumHerstellung, p. 709-736.
History of Molasses [I already scanned it!]

OLBRICH H. Grossbritanniens Rum- und Melasse-importe im 19 Jahrhundert und deren Bedeutung für die einheimische Melassebrennerei, Branntweinwirtschaft 1o6 (1966), p. 144-149.
Britain’s rum and molasses imports in the 19th century and their importance to local molasses distillery

OLBRICH H. Zur historischen Rum- und Melassebrennerei in Deutschland. Beitrag zur Verwertungsgeschichte der Rohrmelasse vom 17. bis 19. Jahrhundert, Branntweinwirtschaft 1o5 (1965), p. 197-2o2.
To the historical rum and molasses distillery in Germany. Contribution to the exploitation history of Rohrmelasse from the 17th to the 19th century

OLBRICH H. Woher stammt das Wort Rum? Branntweinwirtschaft 101 (1961), p. 146.
Where does the word rum come from?

OLBRICH H. Über die Rum-Gewinnung aus Rohr-und Rübenmelasse, Destillateur-Lehrling II (I96I), p. 39-47, 49-51 (Supplement to Branntweinwirtschaft) ; rev. : Z. Zuckerind. 13 (1963), p. 3oo.
About rum extraction from cane and beet molasses

OLBRICH H. Über die Arrak-Gewinnung aus Rohrmelasse, DestillateurLehrling II (1961), p. 57-62 (Supplement to Branntweinwirtschaft) ; rev. : Z. Zuckerind. 13 (1963), p. 236.
About the arrack extraction from molasses

PAIRAULT M. E. A. Le rhum et sa fabrication. Collection des grandes cultures coloniales, Gauthier-Villars 1903, 292 p. fig.
Rum and its manufacture. Collection of Great Colonial Cultures

Pistorius L. J. A. Die Fabrication des Rums in zwei Anweisungen einfach, fasslich und vorteilhaft darstellt. Nebst einem vorzüglichen Verfahren, aus fuselhaftem Branntwein Franzbranntwein oder Cognac zu bereiten. Leipzig: Ernst’sche Buchhandlung; without year. 127 p. ; Review in: Balling’s Zeitschrift des Gewerbewesens 6 (1846/II), p. 678-679.
The fabrication of the rum in two instructions represents simple, comprehensible and advantageous. In addition to an excellent procedure, from fruity brandy to prepare Franzbranntwein or cognac. Leipzig: Ernst’s bookstore

Pott H. H., Nfgr. Rumhandelshaus. Wie Flensburg zur Rumstadt wurde. Eine historische Skizze, herausgegeben anlässlich des Deutschen Schulgeographentages 1964, Flensburg, 1964, 4 p.
How Flensburg became Rumstadt. A historical sketch, published on the occasion of the German School Geography Day

Pott H. H. Nfgr. Rumhandelshaus (Flensburg) : Rum : Sonne der glücklichen Inseln. 1969. 128 p.

Pott. Das Buch vom guten Pott. Eine Rum-Fibel. 2nd Edition, Flensburg (without year), 1o8 p.
The book of the good pot. A rum primer

Pott-Kompass (Journal for Employees of H. H. PoTT, Nfgr. Rumhandelshaus Flensburg) 1967, no 1-5; 1968, no 1-5; 1969, no 1-5; 197o, no 1-5; 1971, no 1-5; not published anymore.

Pouquet J. Les Antilles Françaises. Collection Que sais-je, Presses Universitaires de France, 1971, 126 p.
French West Indies. Collection What do I know

Praktikus. Dextrinausflockung im Rum-Verschnitt. Alkohol-Industrie 64 (1951), no 18, p. 488.
Dextrin flocculation in the rum blend

Ripert F. Essai de synthèse sur le rhum français, Union syndicale des producteurs de sucre et de rhum de l’île de la Réunion (336, rue Saint-Honoré ; Paris 1er), avril 1959, 84 p. dactylographiées.
Synthesis essay on French rum

Ripert F. Le sucre et le rhum à l’île Bourbon, La Revue Française septembre 1971, p. 34-35.
Sugar and rum at Bourbon Island

Rose L. Die Alkohol- und Rumfabrikation in Costa Rica, Z. Spiritusind. 51 (1928), p. 194-195.
The alcohol and rum production in Costa Rica

SAITO K. Notiz über die Melasse-Rumgärung auf den Bonininseln, Zentr. Bact. parasit. ZI (19o8), p. 675-677 ; Oester. -Ung. Z. ZuckInd. Landw. NF 37 (1908), p. 918.
Note about the molasses rum fermentation on the Bonin Islands

Schad. G. F. C. Des Pater Labats, aus dem Orden der Prediger Mönche, Abhandlung vom Zucker… , Nürnberg : G. N. Raspe, 1785, 400 + 48 p. ; (Chapter 26 : Von dem Brandteweine, der aus den Zuckerrohren verfertigt wird, und dessen Zubereitung, p. 332-338) ; further : p. 344-345.
Father Labat, from the order of preacher monks, treatise on sugar …
From brandy made from sugar cane and its preparation

Scherer A. La Réunion. Notes et études documentaires, la Documentation Française, 1967, no 33-58, 6o p.
Notes and documentary studies, French Documentation

Sedeis. Le rhum et le sucre dans les territoires français d’Outre-Mer, Société d’Études et de Documentation Économiques, Industrielles et Sociales, 1949, 101 p.
Rum and sugar in French overseas territories, Society of Studies and Economic, Industrial and Social Documentation

Schaffer E. Geruchsprüfung von Rum, Chem. Ztg. 44 (1923), p. 934.
Odor test of rum

SELL E. . Üeber Cognak, Rum und Arak. Arbeiten aus dem Kaiserlichen gusundheitsamte (a) 6 (1890), p. 335-352 ; (b) 7 (1891), p. 210-252 ; (c) Sonderdruck;
About cognac, rum and arak. Work from the Imperial Health Department

a) Üeber Cognac, das Material zu seiner Herstellung, seine Bereitung und nachherige Behandlung unter Berücksichtigung der im Handel üblichen Gebäuche, sowie seiner Ersatzmittel und Nachahmungen;
About cognac, the material for its production, its preparation and subsequent treatment, taking into account the customary commercial products, as well as its substitutes and imitations

b) Üeber, Rum, das Material zu seiner Herstellung, seine Bereitung und nachherige Behandlung unter Berücksichtigung der im Handel üblichen Gebräuche sowie seiner Ersatzmittel und Nachahmungen;
Over, rum, the material for its manufacture, its preparation and subsequent treatment, taking into account the customary commercial practices and its substitutes and imitations;

c) Separate paper (a + b): Berlin: Springer, 1891

Simon A. Untersuchungen über die Einteilung der Rume von Martinique nach ihrem Verunreinigungskoeffizienten, Oesterr. Ung. Z. Zuckerind. Landw. NF 39 (1910), p. 600-601.
Studies on the classification of Martinique’s rums according to their contamination coefficient

Stretton G. W. P. Induced fermentation in rum production , Int. Sug. Journ. 52 (1950), p. 308-309.

STEINBRINKER H. Bekenntnisse eines Rumschmugglers, Hamburg, 1924
Confessions of a Rum smuggler

Strunk H. Über Rumuntersuchungen, Veröffentlichungen aus dem Gebiete des Militar-stanitatswesens. Heft 52: Arbeiten aus den hygienischchemischen Untersuchungsstellen. V. Teil, Beriin : A. Hirschwald, 1912, p. 26-36.
About Rumuntersuchungen, publications from the field of military stanitatswesens. Issue 52: Work from the hygienic test sites

Teulieres A. L’Outre-Mer Français hier, aujourd’hui, demain. Berger Levrault 1970, 483 P.
French Overseas yesterday, today, tomorrow

WALTER E. Die Grogprobe, ein Hilfsmittel zur Beurteilung von Rum und Arrak, Alkohol-Industrie (1953), no 7, P. 165.
The grog sample, a tool for evaluating rum and arrack

Winkelhausen W. Verfahren zur Vorbereitung von Zuckerlosungen beliebiger Herkunft zur Herstellung einer Maische fur Rum-oder Arrakdestillate. Deutsche Zuckerindustrie 67 (1942), p. 47
Process for preparing sugar blends of any origin for making a mash for rum or arrak distillates

Winkelhausen W. (Holtinghausen i. Oldenburg): Verfahren zur Vorbereitung von Zuckerlosungen beliebiger Herkunft zur Herstellung einer Maische fur Rum-odor Arrackdestillate, Pat. Anm. 106654 am 12.9.1939 Protektorat Bohmen u. Mahren; D. Zuckerhind. 67 (1942) p. 47; DRP 720008 (Kl. 6b, Gr. 1.02) from 13.12.1939.

Wollny G. Martinique-Rum [aus Zuckerrohrsaft und/oder Rohrmelasse], Alkohol-Industrie 77 (1964), no 2, p. 47-49.
Martinique rum from sugar cane juice and / or molasses

Wrede F. Die Rumbrennerei in Übersee und in Deutschland, Z. Spiritusind. 51 (1928), p. 150.
The Rum distilleries overseas and in Germany

Wüstenfeld H., Luckow C. Zur Frage der Begutachtung von Auslandsrum und  Arrak, Korrespondenz ATL (Abteilung Trinkbranntwein und Likörfabrikation im Institut für Gärungsgewerbe Berlin) 18 (1928), p. 23-25.
On the question of the assessment of foreign rum and Arrak

Wüstenfeld H. Luckow C. Esterzahl, Ausgiebigkeit und Qualitat von rum und Arrak sorten des Handels, Mitt. der ATL 20 (1930), no 1, p. 2-6.
Ester number, abundance and quality of rum and arrak types of trade

Wüstenfeld H., Haeseler G. Trinkbranntweine und likore. 4th edition Berlin, Hamburg : P. Parey, 1964, p. 623 ; Chapter : Rum p. 69-78
Drinking liquors and liqueurs

Conduct of the Alcoholic Fermentation Workshops of Molasses and Beet Molasses Products

Sponsor my distilling work simply by sharing the artisan workshop of the Bostonapothecary on social media. Copy, Paste, Share, Support!

Miniac (de) M., 1988. Conduite des ateliers de fermentation alcoolique de produits sucriers (mélasses et égouts). Industries alimentaires et Agricoles 105, 675-688.

This is a very cool paper. It is safe to say it is very significant. Not many new producers will set out to make a rum as described here, but the know-how revealed will help anyone better understand their production.

The big  idea here that will help a lot of people is that of Δ Acid. That is the change in acidity of the fermentation by yeasts and bacteria. Only so much can be expected from yeasts so changes of certain magnitudes can be attributed to bacteria which either represent contamination or intentional flavor production.

Astute connoisseurial consumers may be able to this number like ester counts. For rum to progress, enthusiasts have to get away from nerding about the distillation phase and start exploring fermentation. The first big variable is to Pombe or not, and the second big variable is Δ acidity.

Conduct of the Alcoholic Fermentation Workshops of Molasses and Beet Molasses Products
by Michel de MINIAC*
*Research Fellow at the National Union of Alcohol Distillers Groups

[Melasses implies cane molasses while égouts implies beet molasses according to Professor Fahrasmane.]

I. DESCRIPTION OF THE CIRCUITS AND TECHNOLOGICAL PERFORMANCE RECORDED
1. Process by mother pot (figure 1)
2. Yeast recovery method (figure 2)
3. Continuous and discontinuous (figures 3 and 4)

II. OPTIMIZATION OF THE MAIN PARAMETERS
1. Constitution of musts.
a. Nature of the product used
b. Origin of the water used
c. Addition of acid
d. Nutrient salts
e. Antiseptics
f. Defoamers
g. Industrial Implementation

2. The acidity of the must
a. Action of the acidity (figure 5)
b. Search for an optimal value of acidity (figure 6)
c. Choice of acidity, preferably at pH, for conducting a fermentation

3. The rate of non-sugar
a. Purity of the product used
b. Recycling of non-sugar by vinasses [stillage, dunder]

4. Must formulating conditions and alcoholic degree desired (figure 7)

5. Aeration
a. Action of the air On the yeast
b. Implementation of the aeration

6. Yeast recovery = washing and acid treatment
a. Description of the procedure (figure 8)
b. Conditions for a good functioning (figure 9)

III. Origin and prevent of fermentation accidents
1. Bacterial contamination
a. Origins of contamination
b. Fight against bacterial infection (figure 10, 11, and 12)

2. Yeast contamination
a. Recall of yeast metabolism: Brettanomyces
b. How to prevent the development of Brettanomyces

3. Various chemical toxicities
a. Sulphite
b. Nitrites
c. Organic acids
d. Various additives in sugar

IV. GENERAL CONCLUSION AND PROSPECTIVE RESEARCH
1. Facility design
2. Optimization of some parameters
a. The acidity of the must
b. Using an antiseptic
c. Aeration
d. Use of anti foamers
e. Condition of must formulating

Since 1984, four publications have been made in this journal, sometimes in collaboration with industrialists or research institutes, to determine, under what conditions, it is possible to improve the operation of the molasses alcoholic fermentation workshop. These works are referenced at the end of this talk. We have thought, however, to be useful to the profession, by synthesizing here, observations and measurements made on the sites, or laboratory tests to which they gave rise, in order to give useful advice to the sugar industry which wishes in the near future develop ethanol production.

Initially, the outline of the fermentation circuits currently observed in France will be briefly described, and their performance, advantages and disadvantages can be compared.

In a second step, the key parameters implemented will be reviewed, whatever the process used, in order to underline their action, their importance and the optimal values ​​necessary for the proper functioning of the fermentation.

We will finally see the main causes of fermentation accidents by trying to give precise instructions to prevent them, both in terms of the design of the circuits and their conduct.

I. DESCRIPTION OF THE CIRCUITS AND TECHNOLOGICAL PERFORMANCES RECOGNIZED

All fermenting tanks of molasses observed in France can be classified in two groups, according to the nature of the process used: mother tank or recovery of yeast.

In the first case, the yeast is constantly generated from a fermentor supplied with must and aerated. After fermentation, the yeast biomass is destroyed by distillation and is found in the vinasses.

In the second case, the yeast is concentrated in the form of a cream, before distillation, and is the source of biomass, which is returned to fermentation after washing and acid treatment. These two processes will be described in batch and then in continuous multistage. A comparative table of performance, advantages and disadvantages can then be drawn up.

1) Process by mother tank. (Figure no. 1)

It consists in developing constantly, from a mash lightly loaded with sugar, the yeast biomass which will then be used for the fermentation proper and not reused after. The must is of two kinds, depending on whether it feeds the mother vat (weak must) or the fermentation vat (strong must).

The mother tank: Often made up of several tanks, which are able to produce, in 10 hours of residence time, 30 to 50% of the volume of the fermentation tanks.

In the mother tanks there is simultaneously the production of yeast biomass from a must, and fermentation of this must with a fermentation balance as good as in fermentation itself. The low wort that feeds these vats is low in sugar (70 g/l), so that it can not give a wine higher than 4° GL. The mother tanks are always ventilated. The fermented medium that they produce, will constitute the biomass of yeast which will be sent in the fermentation tank under the name of “pied de cuves” [footing vat].

As mentioned above, it will have to occupy 30 to 50% of the volume of the fermentation tank.

This initial biomass load is of the order of 60 × 10^6 seeds / ml or 3 to 4 g/l of yeast expressed as dry matter.

The whole fermentation goes off at 33°C.

The fermentation tank: of volume generally larger than the mother tanks, the fermentation tanks are never ventilated. We will see later, that it is however desirable to do so, without risk for the fermentation balance as fear some. These vats therefore receive, at regular intervals, a “vat” from the mother vats. The 50 to 70% of the unoccupied volume is therefore slowly filled with must rich in sugar (= 200 g/l) called “strong must”. This progressive filling is called “pouring“. It is usually done with a colder must (= 15°C) so as to absorb the calories from the fermentation which will keep the mixture at about 33°C throughout the fermentation. A cooling device, (exchangers, or water flow on the walls) is nevertheless put in place.

This pouring of the must that will fill the tank is done in 10 to 15 hours. When the tank is full, the fermentation will be completed at 3/4 (6 to 7 °GL). The last degrees will be completed slowly for ten hours, usually called “fall” because it is followed by measurements of densities that decrease due to the transformation of sugar into alcohol. The total fermentation time from the “pied de cuve” is therefore around 25 hours for a wine at 8.3°GL from a total must of 14% sugar. To compensate for the low load of the low must, the wort, called “strong”, poured in fermentation vat should therefore titrate to about 200 g/l of sugar, depending on the volume occupied by the “pied de cuve”.

During the pouring, for reasons that we will see later, the biomass varies little, especially in the absence of aeration.

Although having low productivity, this process is still often used continuously. It has the advantage of being relatively regular insofar as the production of yeast by the mother tanks remains stable. These constitute the heart of the process and must be monitored with the greatest attention (correct pouring, absence of bacterial contamination).

2) Yeast recovery method. (Figure no. 2)

The “pied de cuve” here consists solely of the yeast cream obtained by centrifugation of the wine before distillation. For reasons that we will see later, the yeast is washed, treated with acid and then regenerated in a small tank in the presence of must and air. This regeneration tank produces, after 3 hours of residence time, a “pied de cuve” of a smaller volume than in the process by mother tank, but much more rich in biomass of yeast: of the order of 3 times more. Unfortunately, the productivity is not increased in the same proportions since for 8.3 °GL the fermentation time descends to around 15 hours (instead of 25). Again, there is no air in the fermentation tank and the conditions of casting and temperature are identical.

This process has the advantage of multiplying by 1.7 to 2 the productivity of the vat room, but the process of washing and treating yeasts is often a source of trouble if it is not very well conducted. We will see in a next paragraph how to optimize the parameters.

3) Continuous and discontinuous

For the sake of clarity, we have just described two batch fermentation processes. It goes without saying that continuous fermentation can be applied in both cases. Figure no. 3 gives an overview of a continuous multi-stage fermentation. Five fermentation tanks (sometimes more), are put in series. The first tank is fed with yeast biomass and must. The yeast can then come from either one or more mother tanks, or a yeast cream regeneration tank in the case of yeast recovery. For tanks of identical dimensions the alcoholic degree ranges between 4° and 8°GL, from the first to the last tank. The fermentation times are about the same as those observed in batch.

The two advantages of continuous fermentation are:

Ease of driving, since all the maneuvers of filling and emptying the tanks are eliminated. This of course implies a greater ease of possible automation.

– A better and complete use of the volumes since all the tanks are full and not in filling as it is the case in batch (empty volumes estimated at 20%).

The major, and often feared, drawback of continuous fermentation is the risk of bacterial infection and deposits in tanks that are never emptied and cleaned.

There is a particular case of continuous fermentation with recovery of yeast. This is the BIOSTIL process marketed by the ALFA-LAVAL Company.

There is not here multi-stage, but a single fermenter, and moreover, the yeast is recycled without treatment or washing. For reasons of growth of the yeast, the alcoholic degree can not, under these conditions exceed 5 to 6°GL. The process is, on the other hand, directed towards an increase of the non-sugar dry matter in fermentation by intensive recycling of the vinasses (12%). The fermentation time is very short: 6 hours, which gives a high productivity.

To conclude this chapter, here is, in Figure no. 4 a comparative table which recapitulates all the described processes as well as the advantages and disadvantages of each of them.

II. OPTIMIZATION OF THE MAIN PARAMETERS

The realization of an alcoholic fermentation requires first a good growth of the yeast, then the maintenance in activity of this biomass until the end of the fermentation and even beyond if we plan to recycle this yeast for subsequent fermentations.

The growth of the yeast depends first of all on the constitution of the must then on its implementation, that is to say the pouring; the concentration of sugar and non-sugar will also strongly influence the behavior of the yeast. It should be acidified to protect the fermentation against bacterial contamination. Finally, the yeast recovery method with washing and acid treatment that must be conducted under well-defined conditions, also conditions for the smooth progress of the fermentation. We will review all these parameters by trying to explain their role, to specify their optimal values and the conditions of their implementation.

1) Constitution of musts

The term must is used for any sweet solution ready to be fermented by the yeast, and which will give a wine after fermentation. Its constitution depends essentially on the nature of the products used (here: molasses and beet molasses) and the various additives, often of nutritive nature which are added to the basic product. We will first see the various constituents used and then, by what circuits it is desirable to perform this mixture industrially.

a) Nature of the product used

Regarding the sugar industry, all the products resulting from crystallization are currently used in alcoholic fermentation. Depending on the level of sampling, their purity (sugar / dry matter) varies from 92% to 60%. The rate of non-sugar substances in the wort will therefore vary in the opposite direction of this purity, as shown in the following table, for the different products of crystallization.

These “non-sugars” have a decisive action on the growth of the yeast, but their nutritional quality is however restricted because the calco-carbon purification that precedes their production, has largely eliminated yeast growth factors, (acid amines, proteins and various macromolecules).

We have shown (4) that a minimum of 2% of non-sugar was needed in the medium to ensure sufficient yeast biomass. This shows that an EP [Egoût pauvre, I think this implies any time of molasses] is just valid but that at the syrup level, there is nutritional deficiency. This is however filled by a recycling of vinasse. We will come back in detail about these non-sugar problems in another chapter.

b) Origin of the water used

The sugar product is therefore diluted in water to produce a solution of 14 to 16% of sugar, depending on the desired degree of alcoholic fermentation. Water is rarely an urban water, but rather of natural origin (drilling, surface water) which has the disadvantage of bringing bacterial germs or sometimes some chemical toxins. Good filtration is recommended, in the absence of too expensive pasteurization in energy.

Condensed waters are used: Various evaporation condensates: vinasse, evaporation of juice, distillation, etc.

By their heat treatment, they contain few bacteria, which is a good thing, but on the other hand, they are devoid of mineral elements (obligo or macro-elements) which are sometimes indispensable for the metabolism of the yeast (Ca ++, Mg ++, Co ++, B ++, Mo ++) and found in river waters.

c) Addition of acid

The solution thus obtained has a pH most often greater than 7, or even 8 or 9. It is therefore necessary to add a strong acid to bring the must to pH ranging between 3 and 5 depending on the product used. Sulfuric or hydrochloric acids are most often used. The first is sometimes preferred to the second for reasons of resistance of the materials. Biologically, both acids are tolerated by yeast at things from 2 to 3 g/l wort (expressed in g/l of sulfuric acid). We will return in detail on the role of this acidification which is essentially a protection against bacterial contamination, as well as the optimization and regulation of this parameter which must be done not by the pH but by a measurement of the acidity, expressed in g/l of sulfuric acid. [this is a very key point and part of the big takeaway.

d) Nutritious salts

The most commonly added nutrient salt is di-ammonia phosphate. Laboratory tests have shown that its action on yeast was visible up to the dose of 0.4 g/l of must. It is therefore useless to put in higher doses. We have shown that in this case it is the phosphate ion that is active and not the ammonium. It may be thought that the product is largely supplied in nitrogenous substances, but lacks phosphate to ensure the bio-energetic reactions of the yeast.

Sulphate ions are also necessary for the synthesis of sulfur-containing amino acids, but at a lower dose. Experience has shown that an optimum yeast growth was achieved well before the dose of 0.1 g/l of sulfuric acid.

Sulphate ions can therefore be added at this concentration if the sulfuric acid is not itself used for the acidification of the must.

Other cations are also necessary for the metabolism of yeast, but are often brought by water, as we have said above (eg. Ca + + and various obligo-elements).

Magnesium can be added advantageously in the form of magnesium chloride which is used in sugar refinery to regenerate the resins of the Quentin process. A dose of 5 to 20 millimoles of Mg ++ is sufficient, which corresponds to 0.5 g/l of magnesium chloride. It goes without saying that we must abstain from adding Magnesium in a fermentation of Quentin molasses which already contains a lot of them.

e) Antiseptics

We will come back in detail on this subject in the context of the use of acid and the fight against bacterial contamination. Note briefly that the two products used in molasses fermentation are: sodium fluoride (or ammonium, more soluble) and penicillin.

Fluoride is often used continuously at the soda level of 10 to 20 g/l of must if the pH is close to 4.5 to 5. Its action is effective and keeps the bacterial flora at a low level. It can not be used in the case of yeast recovery because the acid treatment at pH: 2 makes it very harmful for yeasts. It does not seem essential to use yeasts “acclimated” to fluoride, because this acclimatization can be done on the site in a few days.

Penicillin was proposed a few years ago at our initiative. Unstable at pH <4, it is best to use it at pH neighbors of 5, for maximum efficiency.

It is strongly recommended not to use it permanently to avoid inducing the production of penicillo-resistant germs. Its action, in case of severe contamination, is effective in 2 days at a dose of 0.3 mg/l of must.

f) Antifoaming

The gaseous releases in these environments very rich in organic materials give rise to the formation of sometimes very important foams which considerably reduce the usable volume of the vat room. Defoamers are therefore added, most often directly in the fermentation tanks, and not in the constitution of the must. These are most often oils of plant or animal origin (fish oil) that it is good to test beforehand to see if they do not contain inhibitors of growth of yeasts. We will see later that their action can be in some cases stimulating for yeast by participating in the biosynthesis of cell members.

g) Industrial implementation

All these compounds constituting the must must be mixed as quickly as possible to minimize bacterial contamination. The basic sugar product (molasses or beet molasses) is practically sterile (a few germs per gram) in view of the heat treatments undergone in crystallization and the concentration in dry matter obtained (close to 80%). On the other hand, its dilution at the level of the must with all the nutrition additives that are added to it, often allows a very rapid multiplication of the bacterial flora.

It is therefore necessary to avoid what is still practiced in the old facilities, namely wort tanks that are alternately filled and emptied. It is not uncommon to obtain, by this process, musts containing 10^6 bacterial germs per milliliter.

We recommend inline dilution in a baffled mixer (type: Sultzer) of all these products which will be mixed in a very short time and immediately sent to the winery. For the future, in the case of correctly homogenized fermenters, we would propose the pouring of the product without dilution, directly in the tanks. It will be necessary to be able to bring the mixture water, acid, salts by another way and in a very precise way, according to a flow rigorously enslaved to that of the product. This mixture having a pH close to 1, it would be protected from bacterial contamination.

2) The acidity of the must

It is an essential parameter, perhaps the most important, in the conduct of an alcoholic fermentation workshop. While in most fermentations the pH is usually used as a control parameter, it is here that the acidity is measured. We will see successively its action on yeasts and bacteria, what optimal value to give it and why it was chosen in preference to the pH.

a) Action of acidity

It is measured in grams per liter of wort, expressed as sulfuric acid, which is also unusual since it is often used in milli-equivalents. Its action is first of all at the level of the yeast whose growth it slows down. Figure no. 5 shows the evolution of the yeast growth rate (μ) in a molasses must whose acidity varies from 1 to 5 g/l. The decrease of μ is almost linear depending on the acidity of the must. The corresponding pH varies from 5.4 to 4. This fall in the yeast growth rate has the industrial consequence of an increase in the fermentation time and therefore a decrease in the productivity of the vat room. It is therefore not possible to conduct a molasses fermentation at an acidity equal to or greater than 5 g/l, although the pH of 4 is not, a priori, incompatible with the development of the yeast. We will see further the reasons for the choice between pH and acidity. The acidity also has a bacteriostatic action which is very important in a non-sterile environment which will see that bacterial contamination remains the permanent danger. more precise curves of this action will be seen in a later paragraph. Let’s say for the moment that the choice of an optimal value of the acidity remains a compromise between two figures: one too low, favoring the development of the yeasts but also of the bacteria, the other one, higher which must be bacteriostatic without too much hamper the production of yeast biomass.

b) Search for an optimal value of acidity

On molasses, the metabolism of yeasts during fermentation gives rise to some organic acids (including succinic acid or acetic acid) which are responsible for a slight increase in the acidity of the wine compared to the initial must. The difference observed is between 0.5 and 0.8 g/l of sulfuric acid. Let’s call “Δ Acid” this difference between the acidity of the wine and that of the must. In the case of excessive bacterial contamination (> 10^6 germs / ml), the “Δ Acid” then becomes greater than that coming solely from the yeasts. If the acidity of the wort has an effective bacteriostatic action, the “Δ Acid” should remain around 0.8 g/l but not higher.

Figure no. 6 shows the acidity of the must and “Δ Acid” in a factory during a month of manufacture. We find that the “Δ Acid” (dotted curve) returns to the level of 0.5 to 0.8 g/l when the acidity of the wort is between 2 and 2.5 g/l. If the acidity of the must (curve in solid lines) goes down below 2 g/l, its bacteriostatic action becomes too weak and the “Δ Acid” takes values ​​between 1 and 1.5 g/l which means the development of bacterial contamination. We will see in a next chapter the evolution of bacterial contamination in relation with this “Δ Acid” and the action of possible antiseptics. The optimal value of the acidity of the must is therefore between 2 and 2.5 g/l. We see from figure no. 5 it is not optimal for yeast, but it allows a compromise between an average growth of yeasts and a bacteriostatic action limiting the bacterial flora to a non-producing level of organic acids troublesome for yeast.

c) Choice of acidity, preferably at pH, for conducting a fermentation

Some people are surprised at the use of acidity as a control parameter, while a pH measurement, more commonly used, is also easier to measure, regulate or even automate.

First of all, let’s say that the pH is not a safe enough guideline here, because it changes a lot depending on the product used, so the rate of non-sugar varies in a must with 14% sugar. The following table reproduces the pH of musts at 2.5 g/l of acidity according to the sweet product used.

Having noted in the previous paragraph, that a molasses must at pH: 4 could not develop yeast because the acidity of 5 g/l was opposed, we also observe that such a pH: 4 is ideal for fermentation of beet molasses EP¹, or EP² acidity close to 2 g/l. [seems like this would be a significant consideration for dunder rich musts]

The buffering effect imposed by the non-sugar rate thus varies the pH between 2 and 5 for the same acidity. However, the nonsugar is variable, first of all according to the products used, and then, as we will see later, according to the non-sugar rate recycled by the vinasse. It is therefore entirely preferable to use acidity as a regulating factor. In addition, it is more accurate at high levels of non-sugar (10 to 15%) because the pH then evolves very little depending on the acidity, due to the high buffering effect.

Another interest of acidity measurements: they make it possible to constantly carry out a balance of the acid production and to determine this “Δ Acid” which remains an excellent indicator of the bacteriostatic action of the medium and the possible progression of the bacterial contamination.

3). The rate of non-sugar

Non-sugar is essential for yeast growth. It constitutes by its mineral and organic elements an excellent nutritive medium for the yeast. We recently published (4) a very complete work on the action of nonsugar on the yeast metabolism, in relation with the selection of yeast strains resistant to an excess of non-sugar which develops in the medium an osmotic pressure too high. There are two main causes of this variation of non-sugar:
– the purity of the product used,
– the recycling rate of non-sugar by the vinasses.
We will examine them one after the other:

a) Purity of the product used

The non-sugar of the must varies from 1 to 10% depending on the product used. The circuits usually used for the fermentation of molasses show us that the yeast perfectly tolerates 9 to 10% of non-sugar brought by this product and the technological performances that we mentioned above come from such a fermentation.

The use of purer products such as beet molasses gives musts less rich in non-sugar. An increase in the growth of yeasts and fermentation is observed, which shows that, with these products, an optimum dose of nonsugar is approaching around 2 to 4%. With syrups, we are at a level close to 1% of non-sugar, which is quite insufficient to the growth of yeasts.

To summarize :
The non-sugar is in excess in the must of molasses, at an optimal dose with the beet molasses and, there is nutritional deficiency in the must of syrup.

b) Recycling of non-sugar by vinasses.

It is necessary, indeed indispensable, for several reasons. First, in the case of syrups, it is an essential nutritional supplement for yeast. Then, in order to concentrate the effluents and save energy on the vinasse concentration workshop, it seemed desirable to increase the non-sugar fermentation rate up to the dose usually tolerated by the yeast, namely 9 or 10% of the molasses must.

In one of our first works (1) we have shown that at equal concentration the non-sugar of vinasse is more active on the yeast than that coming from the molasses. This is because the vinasse contains yeast autolysate proteins which are much more active growth factors on yeast than beet proteins contained in molasses. In the absence of bacterial contamination, the non-sugar of vinasse contains, in addition, no fermentation inhibitor.

If one recycles the vinasse in an Ep² beet molasses must to lower its purity (76%) until that of a molasses (60%), one observes a slowing down of fermentation. But this mixture remains of a better fermentation quality than molasses of the same purity. This has been demonstrated on laboratory tests (1) and verified in a distillery (2). At the same purity as a molasses, vinasse nonsugar produces an increase in yeast biomass, ethanol productivity and fermentation balance.

It has been desired, for reasons of energy saving, a maximum enrichment of the fermentative medium in non-sugar, at a level well above 10% of molasses must. This is possible with yeast strains selected for this purpose. This has been done in recent years as part of our work at the NATIONAL UNION OF ALCOHOL DISTILLER GROUPS. We will resume the main results already published (4). We currently have some strains of yeast capable of producing in 24 hours of fermentation, a molasses wine of 8°GL containing up to 20% of non-sugar. Under these conditions, the osmotic pressure of the medium becomes considerable and greatly disrupts the metabolism of the yeast on several points:
– Decrease of the growth rate, therefore of the biomass maintained in fermentation.
– Strong biosynthesis of glycerol (osmoregulatory of the cell) which results in a proportional decrease of the fermentation balance. It goes from 61 to 55 liters of alcohol per 100 kg of sucrose consumed when the nonsucre increases by 10 to 20% in the fermentation medium.
– Production of higher alcohols and organic acidity are also influenced by the strains.

For a wine at 8°GL, the nonsugar content in fermentation must therefore remain between 10 and 15%. Beyond these figures, the biological constraints become such that the energy saving sought at the level of the vinasse evaporation is largely absorbed by the decrease of the fermentary yield. It goes without saying that if we accept an alcoholic degree lower than 8°GL, the non-sugar will no longer have this harmful effect on the fermentation balance and it will again be possible to increase the nonsugar in fermentation. This is the choice that has been made in the BIOSTIL process (ALFA-LAVAL) which gives the predominance of non-sugar in relation to the alcoholic degree.

The recycling of vinasse does not therefore pose a major problem on the industrial level. The application that was made in a distillery (2) shows it well. However, the bacterial infection becomes more harmful since some of the organic acids produced by the bacteria are recycled into fermentation by the vinasses. It is therefore necessary to be particularly vigilant bacteriologically. Moreover, a large part of the mineral acidity of the must is recycled by the vinasse. It is not harmful, but it must be taken into account when calculating the acidity of the must. This is another reason to prefer acidity to pH in the regulation of alcoholic fermentations.

4) Pouring conditions and desired alcohol content

The decrease in the growth rate of yeasts under the influence of an excess of non-sugar is largely due to an excessive retention of ethanol in the cell under the action of a strong external osmotic pressure. Ethanol is, directly or indirectly, the main growth inhibitor of yeast. We reproduce in figure no. 7 an already published graph (4), which shows the evolution of yeast growth rate on molasses medium when its alcoholic degree varies between 0 and 8°GL during fermentation. If the growth is little affected by alcohol up to 2°GL, it drops considerably to 5°GL where it becomes almost zero. This is the reason why BIOSTIL process can not exceed 5 to 6°GL at 12% of non-sugar.

In fact, in the continuous fermentation of a single fermenter, the yeast is permanently maintained in a maximum alcoholic medium. If the degree approaches 8°GL, the growth rate becomes too low to regenerate the yeast biomass even in yeast recovery.

We therefore recommend pouring instructions which make it possible to maintain the yeast as long as possible in a weakly alcoholic medium (<5°GL), the excess sugar being not at all inconvenient for the growth of the yeast. We had developed this theme in a work (3) which highlighted how the recovery of yeast biomass in a sweet (and non-alcoholic) medium made it possible to increase the ethanol productivity as much as possible: 8°GL in 5 hours of fermentation. In industrial application two cases are envisaged:

– In discontinuity:
After pouring the stock (from a mother pot or yeast), the must must be poured as quickly as possible so as to dilute as much as possible the alcohol produced by the yeast in a large volume of sweet must. If the tank, once full, has a measure of less than 5°GL, we will have maintained better conditions for its growth than if, from the beginning of a casting too long, we allow it to reach 6 to 7°GL . This is unfortunately what happens in practice, because one usually uses a cold must (10 to 15°C) to “cash” the thermals released by the fermentation. If the must is poured quickly it will have to be warmer so as not to cool the winery, then the calories released later will have to be evacuated by exchangers at the bottom of fermenters.

– Continuously:
The dimensions of the tanks in a multi-stage system (SPEICHIM or VOGELBUSCH type) are made in such a way that the first tank has a residence time such that the alcoholic degree is already very high (close to 5°GL). We believe that lower volumes at the head would establish an alcohol gradient between 1 and 5°GL that would be more favorable for biomass production and therefore productivity. In any case, all the must and the biomass must be poured into the first tank and not staggered over several.

5) Aeration

Aeration has always been essential to the proper functioning of a molasses fermentation, unlike that of beet juice which can be content with dissolved oxygen during diffusion. In the present installations air is added, either in the tanks or in the regeneration tanks of the recycled yeast cream, but not in the fermentation tanks. We would like to evoke successively the physiological action of the air on the yeast and its industrial implementation.

a) Action of air on yeast

The metabolism of yeast can take two ways depending on the presence or absence of air.
– Without air, there is fermentation and production of biomass and ethanol.
– In the presence of air, there is respiration, and only biomass production.

These two paths are sometimes used simultaneously with more or less predominance of one over the other.

On the other hand, an excess of glucose in the fermentation medium blocks the enzymes of the respiratory chain and forces the yeast to follow the fermentative route. This is called “CRABTREE effect” or counter effect PASTEUR.

Without insisting on these problems of metabolism which are not at the heart of the subject, it should however be specified that, given the sugar concentrations found in our fermentations, it is impossible for the addition of air, even in high doses, to divert yeast metabolism to the respiratory tract. There is therefore no reason to fear, as some people think, that an excess of air can lower the fermentative balance in favor of yeast production. We are currently working on this subject, and some interesting results will be published soon in an in-depth study.

The air, at low dose, and always on the fermental path, is however indispensable to the yeast. Indeed, the membrane of the yeast cell is composed of sterols whose biosynthesis requires the presence of molecular oxygen.

Yeast can not reproduce in total anaerobiosis unless the medium contains certain sterols or their precursors which are unsaturated fatty acids. In this regard, some defoamers are probably very active, and a study is underway on this subject.

b) Implementation of aeration

From time immemorial, mother tanks have been ventilated without raising the question of the rate of aeration. This never affected the fermentation balance, which remained close to 62 liters of alcohol per 100 kg of sucrose. This is the proof of what we said at the previous chapter: the air can not be, on molasses medium, a factor of decline of the fermental balance. Our current tests confirm it. Precision although it is about molasses, because we had the example of a distillery which, on more favorable medium, (beet molasses), observed a clear reduction of fermental balance, with excessive production of biomass.

We recommend to ventilate the vats or the yeast recoveries at a rate close to 1 V.V.H. (Volume of air per volume of vat room and per hour). However, the study we are currently conducting shows that the air optimum is reached well before this value. Nevertheless, it remains indispensable to the yeast, even during the course of fermentation. In addition, the physiological constraints imposed by the non-sugar on the yeast require a correct membrane structure to remain active until the end of the fermentation and even beyond, in the case of the recovery of yeast. Air, at a very low dose, is here the necessary growth factor. It has, moreover, the advantage of maintaining the biomass in suspension until the end of the fermentation, when the flow of carbon dioxide is not enough anymore.

This permanent aeration, during all of the fermentation has been practiced for two years with profit in a molasses distillery working by the process of a mother tank. The fermentation balance has even improved, because we have shown that a lack of air can bring down this balance. There was also productivity gain.

In the future, the air will have to be measured, not in flow rate but in % dissolved oxygen, by using oxidation-reduction potential probes. The medium in fact, because of its organic matter load, can solubilize more or less the air sent to the vats. The transfer to the cells is then done by the dissolved part of this air.

6) Resumption of yeasts: acid treatment

We would like to recall first of all that the enrichment of the medium in biomass by the yeast recovery process has the only result, foreseeable indeed, to increase productivity. This increase does not occur in the same proportions as those of the biomass, but allows a production increase of the plant of 30 to 50% compared to the operation in the mother vat of the same volume of vat room. This is, of course, very appreciable. On the other hand, and contrary to the opinion of some, the fermentation balance remains unchanged, whatever the process used. This has been demonstrated in the laboratory and several times verified on industrial sites. This yeast recovery technology must, of course, be conducted in optimal conditions. Before going back over the details of its implementation, it is good to recall the objectives to be achieved on the biological level. The molasses wine contains, besides the yeast biomass, a bacterial flora (104 to 100 germ / m) which is not negligible and it is better not to recycle with the yeasts. The proposed method for reducing the level of this contamination is maintenance at very low pH (<2), by adding acid in the yeast cream. This acid treatment can only be acceptable if the quantities of acid that must be added do not exceed a dose compatible with a correct growth of the yeasts (2 to 3 g/l). We know that the buffering effect of non-sugar counteracts the lowering of pH for such doses of acidity. The acid treatment should therefore be preceded by a washing of the yeast cream with water so as to dilute the non-sugar which will be removed in the supernatant of a second centrifugation. This is the purpose of this treatment which has two phases: a first centrifugation followed by a washing with water. Then a second centrifugation preceding the acid treatment that will kill the bacteria without affecting the yeast biomass. The cream thus treated will be regenerated in the presence of aerated wort and will constitute the basis of a new fermentation (dis-continuous) will feed the first tank of a continuous fermentation multi-staged.

The often stated role of “disgorging” yeasts in water to remove toxins is to be taken with caution. We have ourselves carried out in the laboratory for several months (3), a discontinuous fermentation with recovery of yeast without any treatment of the yeast. In the absence of bacterial contamination, yeast performance remained unchanged.

Similarly, the BIOSTIL process recycles yeast without any treatment. We therefore believe that the purpose of yeast washing is only to get rid of the non-sugar to have a more effective acid treatment.

a) Description of the process

Figure no. 8 gives in detail the implementation of this technology, which has three parts: yeast washing, acid treatment and regeneration of yeasts to give the “pied de cuve”.

— First centrifugation and washing of the yeasts.

The wine from a tank at the end of fermentation is centrifuged a first time. The clarified wine is sent for distillation. The yeast cream obtained: primary cream, generally represents 10% of the volume of the wine and has a lodre [a typo might prevent that from translating] centrifugation pellet of 40%. This cream of yeast is mixed with once its volume of water, then agitated, usually by insufflation of air, for about an hour. This washing gives rise to a primary milk which is centrifuged a second time.

— Second centrigugation and acid treatment.

The second centriguation performed on this milk also aims to concentrate the yeast cream to the maximum (75% of pellet) so as to eliminate the maximum non-sugar substances of the supernatant.

This one also called “small waters” contain about 4° GL. It can not be rejected and must be recycled. Two solutions are possible: either it is sent for distillation, but then there is dilution of the wine and thus additional expenditure of energy at the level of the distillation, or it is put back in the must, which makes an additional source of bacterial contamination. The choice must be made according to the bacteriological quality of the circuits.

This centrifugation gives rise to a secondary cream which is mixed with four times its volume of water. Under these nonsugar dilution conditions, the dose of 2 g/l of acid is sufficient to lower the pH to around 2. The acid treatment of the secondary milk lasts 1 to 2 hours and the agitation is also carried out by air. As we said before, the action of the pH is decisive here to kill the bacteria. This is quite different from the bacteriostatic effect of the acidity of the must during the fermentative process. The acid treatment therefore has two components, pH and time, which must act only on the bacteria and not on the yeasts. This must be watched carefully.

— Regeneration of the yeast and formation of the “pied de cuve”.

It is desirable, after this intense chemical treatment of the yeast, to allow it to multiply rapidly before being put into fermentation, most often without air and alcoholic degree too high. The strong must is quickly poured on the “pied de cuve” which remains aerated, so that the yeasts can begin budding. This regeneration is maintained for 3 to 4 hours. The volume thus obtained is the “pied de cuve” which is sent to the fermentation tank.

b) Conditions for good functioning

We would like to mention here the essential points which condition the correct progress of this technology, namely the production of a biomass of yeast in large quantity, constant and partially cleared of its bacteria.

— Search for an optimal rate of acid treatment.

We observed in the laboratory the behavior of a yeast cream containing yeasts and bacteria, depending on the intensity of the acid treatment that was applied to it (pH, acidity and time). The results are shown in Figure no. 9. We see that the usual treatment (pH: 2) only decreases the bacteria by a power of ten but on the other hand, it is safe for yeasts whose population remains almost stable. More intense treatment may be considered (pH 1.5 or 1). We then observe a very strong bacterial decay. This is quite remarkable, especially since the yeast biomass evolves little during one hour.

If the washing has been effective, an acid treatment with a pH of about 1.5 can be envisaged over a very short time. Note the good resistance of yeasts to such a pH, but the disadvantage remains the high acidity (5 to 8 g/l) to be added for such a pH. Rapid dilution of the “pied de duve” will be necessary to lower this acidity, which is incompatible with good yeast growth.

— Recovery of a yeast biomass in good condition.

At the end of fermentation, under the action of the alcoholic degree and the non-sugar, the survival of the yeasts is rather short. This is accentuated by the deposit in the unstirred vats, the organic acidity coming from the bacteria and sometimes a too high temperature at the end of the fermentation. We therefore recommend some improvements:
– Good thermal regulation: 33°C.
– Agitation at the end of fermentation.
– Aeration can be a good way to agitate, because the air improves yeast survival by its action on cell membrane structures.
– Finally, the tanks whose fermentation has been completed must be distilled without delay.

Maintaining yeast biomass for a few hours in a molasses wine quickly causes yeast autolysis. In addition to this observed decrease, a bacterial flora develops rapidly in the yeast deposit and there is also an additional production of secondary compounds detrimental to a good quality of the alcohol (e.g. aldehydes). To minimize this expectation of “dropping” tanks, the distillation feed must be constantly adjusted to the flow of the vat room. This setting is not easy to monitor, but remains essential for a good regularity of a yeast recovery fermentation.

— Search for the most concentrated yeast cream possible.

This parameter is very important. It depends on the performance and implementation of the equipment used. Yeast pellets of 75 to 80% are currently common values in second centrifugation. The maximum concentration of yeast has two advantages:
– In first centrifugation, it limits the volume of wash water that must be recycled.
– In second centrifugation, it allows to minimize the buffer effect of non-sugar and to lower the pH value with the minimum added acid.

To conclude on this process of yeast recovery, it is undeniable that it allows a significant productivity gain compared to the process by mother tank. But this is often achieved at the cost of technological constraints often difficult to control, not to mention the significant investment in centrifugation equipment.

The process by mother tank, despite its low productivity, however, has some advantages of regularity of operation and simplicity of implementation. We are currently researching under what conditions it would be possible to increase this productivity in order to bring it closer to that of the yeast recovery process. Interesting results have been obtained on this subject and already implemented in a distillery. We will discuss this again in the general conclusion.

III – ORIGIN AND PREVENTION OF FERMENTATION ACCIDENTS

All the parameters we have just mentioned are globally responsible for the smooth running and especially the regularity of a fermentation workshop. A fermentation accident is never a sudden drop in productivity, but a slow decline whose causes are sometimes multiple and often difficult to elucidate. We would like to examine here, under what conditions these accidents occur and what are the means of avoiding them, both in terms of the conduct and the design of the workshop. We will start with the bacterial contamination which remains at the origin of the great majority of fermentation accidents. More recently, a few sites have developed varieties of yeasts producing acetic acid (Brettanomycès), which have seriously disrupted production. We will present the first results of work on this subject, in order to avoid the development of such a flora. Finally, we will see the various chemical toxicities from the products or their recycling, as well as the errors in the conduct of the fermentation workshop.

1) Bacterial Contamination

This remains the weak point of all molasses fermentation circuits. The high non-sugar maintains a pH close to 5, very favorable to the development of the lactic flora. Beyond 100 germs per milliliter, these bacteria produce in the medium an organic acidity which is responsible for the inhibition of yeast growth and therefore the productivity of ethanol. Its action is shown at doses of 0.5 to 1 g/l of acidity produced.

As it is excluded, for reasons of financial profitability, to practice the thermal sterilization of the circuits, we must do everything to ensure that the bacterial flora does not exceed 10^6 germs / ml.

a) Origins of contamination

The sweet product used (molasses or beet molasses) is very little contaminated, given the high thermal scales to which it was subjected during its manufacture. The high concentration of dry matter (80%) also prevents any bacterial growth. These products are however not completely sterile (some germs per range) and therefore provide the necessary seeding medium. At the time of the dilution of musts the bacterial development is very rapid and can reach commonly 10^4 to 10^5 germs / ml.

At this stage there is still no production of organic acid, but the fermentation must be able to take place in the presence of a bacteriostatic agent which prevents the bacterial flora from reaching or exceeding 10^6 germs / ml. The acidity of the must therefore plays this role, as we have already mentioned.

Apart from the must, the various parameters that accentuate the risks of bacterial contamination are as follows:
— The must dilution workshop.
The use of bins is to be avoided. They are difficult to clean and impose in the middle a residence time too long.

Inline dilution is preferable for its low residence time and the possibility of easier automation.

— The fermentation temperature.
It must not exceed 33° C. At higher temperatures (35 to 37 ° C) the growth of bacteria is favored at the expense of yeasts which become less resistant to alcohol and non-sugar.

— The residence time of the dropping tanks.
It promotes the deposition and autolysis of yeasts which is an excellent factor of bacterial contamination.

— The use of flat-bottomed tanks.
It promotes deposits, therefore acts in the same way as before and must be particularly canceled in the case of continuous fermentation.

— The storage of recycled light vinasse.
Non concentrated, vinasse from distillation are sometimes not sterile, especially in the case of vacuum distillation at low temperature. The buffer tank before recycling should be as small as possible, kept warm and often cleaned. It is also a source of contamination.

— The washing water of the fermentation gases.
The alcohol carried by the carbon dioxide is recovered by a washing column. The alcoholic water must preferably be sent for distillation because it contains a non-negligible bacterial flora. The same is true of yeast wash water (or “small water”).

b) Fight against bacterial infection

Apart from certain instructions for conducting or designing the installations, the fight against bacterial infection requires permanent monitoring of the bacterial flora at all levels of the installation. The main points to watch are:
• the dilution of musts,
• the tank at the end of fermentation,
• the mother-pot eventually
• acid-treated yeast cream (in case of yeast uptake).

Counting techniques are multiple. We use petri dish spreading with M.R.S. at 0.5 g/l of actidione. The counts can be done in 24 hours, if the incubation temperature is raised to 35-36° C. Recall the significant parameter of the bacterial infection: the “Δ Acid”. It is a fast, simple measurement, the result of which is immediate. It measures the difference between the acidity of the wine and that of the must during pouring. In the absence of bacterial infection, it is maintained between 0.5 and 0.8 g/l and above all it must remain constant.

Its increase of 0.5 g/l is significant of a contamination. We refer you to figure no. 6 which traces the evolution of “Δ Acid” according to the bacteriostatic action of the acidity of the must.

When this is insufficient and there is an increase in “Δ Acid” and bacterial flora, we can use some antiseptics.

We will mention two that are commonly used: sodium fluoride and penicillin (sodium G. de Rhone-Poulenc).

Figures no. 10-no. 11 and no. 12 show the comparative action of the acidity of the must, sodium fluoride and penicillin On:
• the growth rate of bacteria,
• the “Δ Acid” product,
• Yeast biomass.

As we have already seen, the acidity of the must, if it has an action on the growth of the bacteria, also has action on the yeasts. It is found that beyond 2 g/l its action is reflected on the yeasts. At lower values, the yeast is hampered by the acidity of the bacteria as shown by the “Δ Acid” curve (2-5 g/l). The use of a good antiseptic acting on bacteria and not on yeasts is here very appreciable.

Sodium fluoride (between 5 to 20 g / hl of must) has a weak action on the bacteria, but allows a good regeneration of the yeast biomass by a very correct attenuation of “Δ Acid”.

Penicillin is more effective on the bacterial flora. Its dose should be 0.3 mg/l (or, 16.5 million international units per gram). Beyond, Its action is not better, but it does not risk to hinder the yeast.

2) Yeast Contamination (Brettanomycés)

The fermentation of molasses is made by the yeast Saccharomycés cerevisiae. In most cases, bakers yeasts are used for their ease of use. It is possible that so-called “wild” yeasts develop in the medium since no sterilization is performed at the product level. If their growth rate is sufficient, they can maintain and produce alcohol without hindering the fermentation of the bakers strain initially implemented.

However, serious fermentation accidents have occurred, for 2 to 3 years, by the contamination of a yeast which eliminates the original strain and is nevertheless unable to perform the fermentation with a suitable productivity.

Three cases have so far been observed. The incriminated microorganism was in all cases: Brettanomyces intermedius.

a) Recall of yeast metabolism: Brettanomyces.

In 1940 M.Th. CUSTERS describes this yeast in his thesis, by its peculiarity of developing a negative PASTEUR effect, which was later called the CUSTERS effect.

Indeed, the alcoholic fermentation of this yeast is not inhibited (PASTEUR effect) but stimulated by the presence of air. In addition, its fermentation is accompanied by a high production of acetic acid.

We have recently shown that the acidity of the must, in values of 3 to 4 g/l, stimulates the growth of this yeast while it prevents the development of Saccharomyces cerevisiae.

b) How to prevent the development of Brettanomyces.

Such contamination is the consequence of two-level driving errors in the workshop.
– An excess of air,
– An excess of acidity of musts.

Under these conditions, the new yeast strain (Brettanomyces) implants in the medium, to the detriment of Saccharomyces cerevisiae whose growth rate is greatly reduced compared to that of the infecting strain. In addition, there is then biosynthesis of acetic acid by Brettanomyces which eventually is an inhibitor and the fermentation is considerably slowed or even incomplete. We are currently very poor in handly this type of contamination. In all cases, a complete liquidation of the vat room is necessary and the restarting can only be done after a thorough cleaning and disinfection of all the circuits.

The first accidents of this kind appeared on a BIOSTIL implementation site. Note that the ALFA-LAVAL Company recommended the use of Saccharomyces pombe instead of Saccharomyces cerevisiae for reasons, announced, for better resistance to the osmotic pressure of non-sugar, but which would require, to increase the low growth rate of Saccharomyces pombe, a very strong aeration. This, combined with a poorer control of the acidity of musts, is probably responsible for the accidents observed on the site and which were due to the invasion of the medium by Brettanomyces. [return of our hero Pombe in a high productivity environment]

Subsequently, in two other factories, a similar phenomenon appeared, and it seems, again, that this is the result of errors of conduct in the air or acidity. Laboratory tests clearly show that with a very low aeration (0.5 V.V.H.) and an acidity of between 2 and 2.5 g/l, Brettanomycès strains can not develop in molasses medium. It is therefore necessary to master these two parameters perfectly. We are currently working on aeration and will soon propose very specific instructions on this subject. As for the acidity of musts, it would be desirable to be able to control the bacterial contamination without resorting to an excess of acidity. Either by a better bacterial cleanliness of the medium, or by the use of a correct antiseptic allowing to work with a low level of acidity of the musts (1 to 1.5 g/l).

3) Various chemical toxicities

Apart from certain contaminations, the yeast can be hampered in its development by different products which have been introduced or have originated, in the manufacture of the sugar product.

a) Sulphites

Present in sugar products, its toxicity appears in fermentation from 1 g/l of must. It also varies according to the degree of binding of SO2 with other organic substances, and also according to the pH of use.

b) Nitrites

They are often formed in tower diffusers that facilitate the development of anaerobic nitrous fermentations. Inhibition of fermentation appears from 0.3 g/l of nitrates. On the site, the presence of red nitrous vapors is often visible in open tanks. It is therefore necessary to carefully monitor the bacterial contamination of diffusions that can develop an anaerobic flora of nitrous bacteria.

c) Organic acids

We have shown in molasses the presence of organic acids (type: lactic) (2) which are released at the time of the acidification of musts. These acids act on yeast, such as those we have already spoken of at length, which are produced by the bacterial contamination in fermentation. They come here from diffusion where an identical flora can also develop. The sugar industry is well aware of these problems, which it solves with antiseptics (formalin and others). It should be noted that increased monitoring at this level will be beneficial to the fermentative quality of the molasses type sweet product. Organic acids are indeed heavy products that concentrate in crystallization.

d) Various additives in sugar

Most of the additives used in sugar (biocides, defoamers, gutters, pressing additives, ect …) are found at a concentration multiplied by ten years in molasses. Some of these substances may be harmful to yeast. It is therefore necessary to make sure before use.

IV. GENERAL CONCLUSION AND PROSPECTIVE RESEARCH

As we said at the beginning of this work, we wanted to give an account of the conditions under which the various molasses fermentations workshops operated. We set ourselves the goal of proposing an optimization for each parameter and the overall design of the installations. We would like to return here, on a few key points that will determine our prospective research in the coming years at the NATIONAL UNION OF ALCOHOL DISTILLER GROUPS.

1) Facility design

These are designed according to two main principles vat-mother or recovery of yeast. In both cases the fermentation balance remains the same, only the productivity is increased by the yeast recovery process. This is often done at the cost of numerous technological constraints and often difficult to control.

For our part, we want to develop the process by mother tank by trying to increase its productivity by optimizing certain parameters stimulating the development of yeast biomass. In recent years, we have developed aeration throughout the fermentation process. We give as an example, the case of the ORIGNY-SAINTE-BENOTTE distiller which could thus significantly increase the productivity of its vat room, operating by mother tank.

The average figures for the last campaign are:
– Alcoholic degree of the wine: 10.6 g/l,
– Non-sugar wine dry matter: 10.5% (13.5% on vinasse),
– Fermentation time: 27 hours,
– Fermentation balance: 61.6 liters of alcohol per 100 kg of sucrose,
– Productivity of ethanol: g/l/h: 3.10.

The productivity is thus close to that obtained by yeast recovery, without having the constraints of this process.

2) Optimization of some parameters

a) The acidity of the must

This must remain constant in order to constantly appreciate the “Δ Acid”, a witness of bacterial contamination. We propose that it evolves between 2 and 2.5 g/l of must, in order to avoid contamination by Brettanomycès.

b) Using an antiseptic

Penicillin gives good results but can not be used permanently for fear of giving birth to penicillo-resistant germs. Sodium fluoride is used only in the mother vat, because the acid treatment process makes its action very harmful for yeasts. Traces of hydrofluoric acid destroy the yeast biomass. The search for an antiseptic that can supplement the bacteriostatic action of the must acidity would have many advantages.
Gain of productivity by operation with weak acidity (1 to 1.5 g/l),

Non-contamination by Brettanomycès at low acidity.

Recycling vinasse facilitated by a weak organic acidity in the absence of bacterial infection.

We are in contact with antiseptic producers working on this subject in collaboration with us. The use of a new product at this level remains however subject to some conditions, besides its biological action:
Does not interfere with yeast, in a wide range of use against bacteria.
Does not give pollutants in the alcohol after the heat treatment of the distillation.
Does not give toxic products in concentrated vinasse, often used for livestock feed.

An important but still useful work remains to be done in this field for the coming years, especially in the context of large production plants (5,000 hl of pure alcohol per day).

c) Aeration

We have recently shown in the laboratory that this ventilation remains indispensable, but could be reduced to a minimum. More precise figures will be given soon, as well as the methods of measurements on the sites by probes of potential of oxydo-reduction.

This decrease in air should also help to avoid contamination by Brettanomyces whose alcoholic fermentation is stimulated at high levels of air.

d) use of antifoam

According to researchers specializing in this field, some defoamers may contain unsaturated fatty acids that would enter the biosynthetic pathway of yeast membrane sterols. They would participate in the survival of yeasts under adverse conditions of alcohol and osmotic pressure. A study is underway on this subject and will lead to the action of defoamers used either in distillery or at different stages of the sugar industry and which are found more or less chemically transformed into molasses.

e) Terms of casting

Maintaining a low alcohol environment at the start of fermentation is also a yeast growth factor. It can be promoted especially continuously by sizing the heads of tanks imposing the fermentation medium very short residence times to obtain an alcohol gradient less than 5 ° GL.

We would not want to finish this work without telling the Industrialists that we have tried above all to inform them and help them. We hope that this work, which is necessarily incomplete and uncriticized, will elicit from them comments and information that may complement or even modify the broad lines of research that we will pursue over the next few years for them.

BIBLIOGRAPHIC REFERENCES

(1) M. de MINIAC, Fermentation alcoolique des sous-produits de sucrerie. Ind. Aliment. Agric. 1984, 101, 3, 123-135.

[Alcoholic fermentation of sugar by-products.]

(2) G. ALARD, M. de MINIAC. Recyclage des vinasses ou de leurs condensats d’évaporation en fermentation alcoolique des produits sucriers lourds (mélasses et égoûts). End. Aliment. Agric. 1985, 102, 9, 877-882.
[Recycling vinasses or their evaporation condensates in alcoholic fermentation of heavy sugar products (molasses and beet molasses)]

(3) M. NOMUS, M. de MINIAC. Gain de productivité d’éthanol en fermentation alcoolique des produits de Sucrerie (mélasses et égouts) Ind. Aliment. Agric. 1985, 102, 971-985.
[Productivity gain of ethanol in alcoholic fermentation of sugar products (molasses and beet molasses)]

(4) M. de MINIAC. Sélection de souches de levures pour la fermentation alcoolique de milieux mélassés enrichis en non-sucre de vinasse. Ind. Aliment, Agric. 1987, 104, 425-439,
[Selection of yeast strains for the alcoholic fermentation of molasses enriched in non-sugar of vinasse]

 

Lost rum of the Japanese Bonin islands. 1908

Sponsor my distilling work simply by sharing the artisan workshop of the Bostonapothecary on social media. Copy, Paste, Share, Support!

This was translated from German as part of operation #RumBabelFish

Note about the molasses rum fermentation on the Bonin Islands (Japan).
By K. Saito, Tokio.

The inhabitants of the Bonin Islands prepare an alcoholic beverage from cane sugar molasses, of which they produce about 300 koku [1 koku = 180.39 L] per year.

To make this beverage, pour the moderately diluted molasses into barrels that are left to stand still in a warm room. As soon as the fermentation begins after a few days, a white foam cap is created. It gradually becomes larger and denser, until finally, at the end of the fermentation, the whole surface of the liquid is covered with foam. The fermented mass is then distilled. This gives clear, colorless rum of a somewhat acidic taste, the composition of which, according to my own experiment, is characterized by the following analytical findings, namely:

Specific Gravity (at 15° C)                        0.95429
Alkohol (Volume %)                                  38.537
Acid (as acetic acid)                                   0.174 %.
Acetic acid reaction                                   clearly
Furfurol reaction                                        clearly
Fusel oil                                                          trace

In the molasses I found a copious amount of a yeast species. which was isolated from it. The investigations of this yeast carried out by me have given the following results:

The yeast forms on Kojidekokt [koji decoction?] or wort at 30 ° C a delicate, dry, white Kahmhaut [film yeast], which sinks easily to the ground. The cells are not variable in shape, usually round or oval, occasionally containing one or more vacuoles, 6-10 μ in diameter. Not infrequently, sausage-shaped cells also occur (FIG. 1). Giant colony on beer wort gelatin shows an uneven and dry surface of floury-white color. The development apparently takes place with preference in higher temperatures; in beer wort z. For example, the maximum temperature is 38 ° C, the minimum is 10 ° C, while 30 ° C is the most desirable for growth.

The spores form at least 18 to 30 ° C, but the time of sporulation is not sufficiently determined at a number of different temperatures. The skin on beer wort or Kojid kokt contains an ample amount of Asken. The spores are usually round, sometimes a little compressed or flattened. Its diameter is 2.5-3 μ. 1-4 spores develop in one cell, usually 2-3, and germinate by ordinary budding (Figure 2).

Fig. L. Cells from young skins. (X 900.)
Fig. 2. Sporulation and germination. (X 900.)

4.8 Vol. Alcohol [the fermented mash contained 2.4% alcohol] formed in the Kojidekokt (15 ° Balling) after 7 days at 30 ° C; Sown in wort, but only traces of fermentation appeared. In both cases, the yeast develops on the surface of the liquid and sinks slightly to the bottom.

In fermentation experiments in a hollow slide, the yeast fermented only dextrose and fructose, while fermentation did not occur in nutrient solution containing cane sugar, without any indication of the formation of reducing sugars. Skin formation appeared abundantly.

This yeast still grows at an alcohol content of 20 vol. in the Kojidekokt. Exuberant skin formation occurs even in such a concentrated nutrient solution) as 50 percent glucose.

It is clear from the above descriptions that we have here a yeast which must be reckoned to the genus Pichia. Most likely is Pichia californica (Seifert) Klöcker, which was first found in California red wine; but the above-mentioned descriptions are not crucial, because the spore curve in my Hefeart [yeast species?] not yet established.

Since this yeast is only able to ferment dextrose and fructose, it is easy to understand that the alcohol formation in the cane molasses takes place only at the expense of the invert sugar contained therein. My yeast is the causative agent of alcoholic fermentation in molasses, but it does not necessarily have to be active or present as long as rum preparation is dependent on spontaneous fermentation.

Botanisches Institut, Tokio, Mai 1908.

 

The Formic Acid Component of the Volatile Acidity of Rums

Sponsor my distilling work simply by sharing the artisan workshop of the Bostonapothecary on social media. Copy, Paste, Share, Support!

Jouret C., Pace E., Parfait A. 1990a. L’acide formique composant de l’acidité volatile des rhums. Industries alimentaires et Agricoles 107, 1239 – 1241.

The formic acid component of the volatile acidity of rums
By JOURET C. *, PACE E. *, PARFAITA.**
*INRA – Station expérimentale d’Œnologie de Pech Rouge, Gruissan
**INRA – Antilles Guyanne – Pointe à Pitre Cedex

Summary

The dosage of formic acid was carried out on rums of diverse types (agricultural, molasses, large aroma), aged or not in oak barrels using a specific enzymatic method.

The rates recorded vary according to the origin of the samples and show the influence of several factors: the role of microorganisms and that of the wood of the preservation containers appear to be of importance.

Introduction

Formic acid is the first acid in the series of fatty acids that make up the Volatile acidity of rums. In the legislative concept of volatile acidity are all the organic acids, in the free state or in the salified state, drivable by water vapor [volatile by steam distillation]; lactic, succinic and sorbic acids, as well as carbon dioxide and sulfur dioxide, are not taken into account in this measure.

Various authors (MAUREL A. et al., 1965; PARFAIT A. and SABINE, 1975) have studied the global volatile acidity of rums, FAHRASMANE L. et al. (1983) and NYKAINEN L and SUOMALAINEN H. (1983) presented quantitative data for various Volatile acids found in sugarcane alcohols. In addition, LEHTONEN H.J. and SUOMALAINEN H. (1977) have demonstrated the presence of a particular volatile acid in rums: 2 ethyl 3 methyl butyric acid.

However, published results on the levels of formic acid in these alcoholic beverages are rare (KERVEGANT D. 1946, TER HEIDE R. 1986) and it therefore seemed interesting to dose this volatile acid in the different types of rums existing on the market to have a better knowledge of the chemical composition of these eaux-de-vie.

Analysis technique

We have chosen for its specificity and simplicity, the enzymatic assay technique proposed by the company Boehringer-Mannheim.

The principle of the assay is based on the oxidation of formic acid quantitatively to carbon dioxide, in the presence of formate dehydrogenase (FHD) by nicotinamide adenine dinucleotide (NAD).

The amount of NADH formed is stoichiometric with respect to the oxidation of formic acid. NADH is measured by increasing the absorbance of the medium at 365 nm.

Formic acid level of rums (in mg/l of rum at 50° GL)

We followed the dosing method indicated by the supplier of the Analytical Certificate with some slight modifications to adapt it to the problems of the brandies: on the one hand, by evacuating under a vacuum to half to reduce the volume of the sample; which makes it possible to get rid of volatile substances interfering with the assay (excessive ethanal, ethyl formate, formaldehyde, etc.); on the other hand, rums aged in barrels and thus colored were diluted to half or quarter of the intensity of their coloring before the vacuum evaporation operation. This is followed by a charcoal treatment (50 mg for 5 ml) and a fine membrane filtration.

Reproductivity is 5% in the worst cases.

Results and discussion

The assays were carried out on the different types of rums from the French West Indies of well-known origin: rums made from cane juice, rums from molasses, white and aged in oak barrels, rums grand arôme (obtained from a particular fermentation medium), as well as samples from an experiment on rums wooded and stored for 3 years in spent oak barrels.

The results expressed as mg of formic acid per liter of rum at 50° GL were collated in the following table.

It can be noted, very generally, that white agricole rums are poor in formic acid: 1.3 mg/l on average; the white rums of molasses are already richer with amounts of the order of 3.5 mg/l and this increase in the formic acid content is important for rums aged in oak barrels, as well as for white grand arôme rums. There are, however, some exceptions to this finding.

These quantitative differences can be explained by the multiple pathways of the biological formation of formic acid and, of course, by the technological processes used in the elaboration of different rums.

We can, therefore, question, first of all, the richness in formic acid of the various raw materials used in the manufacture: juice of sugar cane, molasses, vinasse [dunder, stillage].

Then, the influence of the microorganisms involved in the transformation; if the yeasts produce practically no formic acid from the sugars during a normal alcoholic fermentation, on the other hand, different microorganisms can degrade the sugars or other substrates present in the fermentative medium (AHRENS I., DIZER H. 1978) to give formic acid.

During the elaboration of rums, the health status of sugar canes (effect of pre-harvest burning, the time elapsed between cutting and implementation, etc.) as well as the conditions for obtaining and preserving molasses and vinasses; the state of maintenance of the premises and equipment; the microbiological quality of the water used for the extraction of sugar or the dilution of molasses; fermentation techniques (seeding, temperature control, …) lead to considerable variations in the composition of the fermentation flora and hence to the quality of the rums (GANOU – PARFAIT B. 1984, GANOU – PARFAIT B., FAHRASMANE L. et al 1989).

Also involved are the physicochemical phenomena that occur during the more or less advanced heating of carbohydrate substances in obtaining molasses or during distillation (SUGISAWA H. 1966, COTTIER L. et al., 1989). Vinasse, used only in certain rum fabrications or for grand arôme rums, is a bottoms product and, consequently, is richer in polar compounds, especially organic acids.

Finally, during the storage in barrels, several physicochemical phenomena known for the aging of wood spirits can be taken into account; the concentration of polar components resulting from the evaporation loss of volatile compounds as well as the oxidation of alcohols to acids. These two elements must, of course, play a reduced role, given the average volume losses of 5% per year and the low level of methanol existing in the rums. The role of wood appears, a priori, more important. In fact, the barrels undergo, during their manufacture, a heating for the bending of the staves and often a burning of the inner wall. The resulting degradation of carbohydrate elements gives furfurolic components and formic acid. This path is more or less active depending on the degree of burning and the stage of use of the barrel.

Depending on the situation, several of the elements thus rapidly defined may be added to explain the general observation and the special cases.

Thus, white agricole rums have reduced levels of formic acid because cane juice contains little. For No. 4 and No. 14 samples and to a lesser extent No. 13 and No. 10, the significant enrichment in formic acid was certainly bacterial in origin because the water required for their preparation was derived from a water table that became brackish and loaded with various microorganisms after a very dry period.

White rums from molasses contain more formic acid because the raw material used provides more for various reasons (concentration, heating, preservation). No. 4, particularly rich, is a rum having had a manufacturing accident due to bacteria present in the water. No. 14 and 15 are rums that have been rectified during distillation to reduce non-alcohol components. The degree of distilling between 92° GL and 93° GL makes it possible to eliminate, in particular, polar elements such as acids.

Apart from the grand arôme white rums whose rich formic acid is explained by their conditions of preparation (molasses with the addition of vinasse, yeast and bacterial flora complex), the rums aged in barrels are loaded with formic acid : No. 9 and No. 10 agricole rums and No. 4 molasses rum have relatively low levels as they have been kept for only 6 months in barrels and have been classified here as “Old” to facilitate the presentation of the results. The other samples have at least 3 years of wood storage, which is legally the minimum period to qualify as Old rum.

We have, moreover, a more precise idea of ​​the increase of formic acid in the rum due to the preservation in barrel with the experimentation concerning the addition of boise [wood extract]. The example, white rum, is a mixture of agricultural rum, and two rums derived from molasses, one with a low non-alcoholic coefficient, less than 100 g/hl / AP [pure alcohol], the other with a high non-alcoholic coefficient, more than 225 g/hl / AP. It contains 1.80 mg/l of formic acid. It reaches, after 3 years, a rate of 11.50 mg/l. Addition of boise at the start causes an increase in the rate to 4.40 mg/l, the two batches of boise rums reach 12.60 mg/l after 3 years of storage. The barrels used in this test had already been used for several years to try to avoid an excessive interaction of the polyphenolic compounds of the barrel compared to those of the boise.

Conclusion

In a very general way, we can say that the rate of formic acid in rums remains in the range of figures found for other eaux-de-vie, white or aged: the composition of the raw material, thermal degradation of substances carbohydrates, as well as the concentration of acids due to the evaporation of less polar volatile substances, the equilibrium formic acid / ethyl formate, the oxidation of methanol present in the initial brandy, the role of wood during barrel preservation are biochemical and physicochemical factors that play a significant role in the formic acid composition of beverage alcohol.

However, the intervention of various microorganisms, other than yeasts, can lead to a significant increase in the formic acid content of white rums. If a specific microbial activity is desired for obtaining the very strong rums, that are the rums grand arôme, other uncontrolled bacterial interventions give alcohols with defects more or less serious. The determination of the level of formic acid can then be presented as a complementary element of appreciation of the conditions for the production of a rum and the evaluation of its quality.

Bibliography

AHRENS I., DIZER H. – Zur Frage der Ameisensäurebildung durch Schimmelpilze und der Sterilität von Gärröhrchen. FLUESS. OBST, 1978, 45, 428-430.

COTTIER L., DESCOTES G., NEYRET C., NIGAY H. – Pyrolyse des sucres, analyses des vapeurs de caramels industriels, IND, AGRI. ALIM, 1989, 106,567-570.

FAHRASMANE L., PARFAIT A., JOURET C., GALZY P., PACE E. – Étude de l’acidité volatile des rhums des Antilles Françaises, IND, AGRI, ALIM, 1983, 100, 297-301.

GANOU-PARFAIT B. – Contribution à l’étude des bactéries des milieux fermentaires de rhumerie. Thèse USTL MONTPELLIER, 1984.

GANOU-PARFAIT B., FAHRASMANE L., GALZY P., PARFAIT A. – Les bactéries aérobies des milieux fermentaires à base de jus de canne à sucre. IND, AGRI, ALIM., 1989, 106, 579-585.

Ter HEIDE R. – The flavour of distilled beverages in FOODS FLAVOURS, Part B. The Flavour of beverages, ELSEVIER, 1986.

KERVEGANT D. – Rhums et eaux de vie de canne, Ed. du Golf. Varnas, 1946.

LEHTONEN M. SUOMALAINEN H. – Rum – in Economic Microbiology. AH, ROSE Ed. Woll. Alcoholic beverages, Academic Press London.

MAUREL A., SANSOULET O., GIFFARD Y. – Étude chimique et examen chromatographique en phase gazeuse des rhums, Ann, Fals. Exp, chim, 1965, 58, 29-303.

NYKAINEN L., SUOMALAINEN H. – Aroma of beer, wine and distilled alcoholic beverages. D. REIDEL Publishing Cie, 1983.

PARFAIT A., SABIN G. – Les fermentations traditionnelles de mélasse et de jus de canne aux Antilles Françaises. IND, AGRIC. ALIM, 1975,92,27-34.

SUGISAWA H. – The thermal degradation of sugars, 2/the volatile decomposition products of glucose caramel, J. Food, Sci, 1966, 31,381-385.

 

Glycerol in the alcoholic fermentation of molasses and sugar cane juice

Sponsor my distilling work simply by sharing the artisan workshop of the Bostonapothecary on social media. Copy, Paste, Share, Support!

Parfait A., Jouret C., 1980. Le glycérol dans la fermentation alcoolique des mélasses et des jus de canne à sucre. Industries alimentaires et Agricoles 97, 721-724.

Le glycérol dans la fermentation alcoolique des mélasses et des jus de cannes à sucre
by PARFAIT A. *, JOURET C. **
with technical collaboration from G. SABIN and Madame G. MIGLIORI

(*) C.R.A.A.G. Station de Technologie, Guadeloupe.
(**) C.R.A. de Toulouse, Laboratoire de Technologie des Produits Végétaux, Auzeville.

Summary

Authors have specified the influence of various factors (mode of conduct, pH, seeding rate, sugar content, yeast species) on the amount of glycerol found in rums.

They have also shown that glycerol can serve as a carbon substrate for various bacteria and give, as a result, derivatives having a negative role on the organoleptic qualities of this eau-de-vie.


Glycerol is a secondary product formed by the metabolism of sugars during alcoholic fermentation.

Depending on the conditions, a more or less important fraction of the sugars is thus transformed into glycerol. This results in different values of the fermentation yield.

Genevois (1936) proposed an equation between various byproducts of alcoholic fermentation

2A + B + 2M + H + 5S = ε = G

A, B, M, H, S and G being respectively the molar concentrations of acetic acid, 2-3 butane diol, acetoin, acetaldehyde, succinic acid and glycerol. This equation has been the subject of much work and has been confirmed by Lafon (1955). It can be considered valid in 90% of fermentations.

Subsequently, Nordstrom (1968) and Oura (1977) showed that there was a correlation between the redox potential of the fermenting medium and the formation of glycerol.

According to Oura, the formation of succinic acid is related to the production of glycerol and has the same purpose: to balance the excess of reduced nucleotides.

Glycerol, whose physiological interest for yeast appears to be small, seems however to play a significant role in the regulation of compounds such as pyruvic and succinic acids that enter, instead, in the formation of constituents of the cell. Similarly, glycerol, via its phosphoric ester, L-α glycerophosphate, combines with activated fatty acids to give phosphatidic acid. This last body leads to lipids. This same ester allows the use of glycerol by many breeds of yeasts as a source of carbon. Although the low volatility of glycerol explains its absence in rums, it has been possible to determine various compounds from its degradation. These generally have a negative effect on the organoleptic qualities of eaux-de-vie.

Since the work of Warcollier and Le Moal (1932) on ciders and those of Serjak et al. (1954), we attribute to the action of lactic acid bacteria the appearance of acrolein in spirits.

Dubois et al. (1973) identified two acrolein derivatives in an abnormal taste rum: ethoxy-3-propanol and ethoxypropane. These compounds are not directly responsible for the unpleasant flavor of the rum studied but can serve as indicators.

Smedt and Liddle (1976) have correlated the presence of allylic alcohol (2propene 1 ol [I think that is correct nomenclature]) with some bad tastes in various types of spirits. They also showed a relationship between the contents of this alcohol and those of ethoxypropane.

Thus, the glycerol which is at the origin of acrolein (and products derived from this aldehyde) following metabolic pathways not completely elucidated, can therefore be degraded in fermenting media based on cane juice and molasses.

Given these biochemical and technological considerations, it seemed interesting to specify some parameters of the production of glycerol in the fermentation of the basic products of the different types of rums.

Experimental Protocol

Glycerol was determined according to the enzymatic technique of Eggstein and Kuhlmann (1974) after defecation of natural media with lead acetate.

Samples of fermented media were taken from industrial plants previously described by Sabin and Parfait (1975). Just remember that the following raw materials cane juice, syrup and molasses, are used respectively for the development of agricultural rums, syrup and industrial.

The results are reported in Table 1.

Table 1.
Glycerol content expressed in g / l in fermentation media of different types of rums

399/5000
Following these measurements, tests were conducted in the laboratory to specify the glycerol formation conditions according to the pH, the fermentable substrate concentration, the yeast seeding rate, the species and the yeast strains.

The growing conditions were as follows:
—Molasses: 300 g / l,
—seeding rate: 1 g /,
—fermentation temperature: 30 ° C.

The seeding was carried out using yeast creams in order to eliminate the glycerol fraction that could be brought by the starter.

The yeast strain saccharomycès cerevisiae used is the No. 493 of our collection, isolated from a natural fermentative medium of agricultural rum.

Influence of pH:
Initial pHs were set at 3.5 – 4.0 – 4.5 – 5.0 – 5.3.

The evolution of the glycerol level during the fermentation was regularly monitored.

For example, for the medium at pH 40, the following figures were noted:

These figures vary very little according to the different pHs tested.

Influence of molasses richness:

The molasses concentrations of 150 g/L, 200 g/L, 250 g/L and 300 g/L were varied, the seeding rate was 1 g/L, the fermentation temperature 30° C and the initial pH set to 5.

The glycerol levels found were in order: 1.5 g/L, 1.7 g/L, 2.3 g/L and 2.5 g/L. They follow the same progression as that of sugars.

Influence of seeding rate:

By changing the seeding rate from 0.25 g/L, 0.50 g/L, 1.0 g/L, 2.7 g/L and 2.5 g/L, 4.0 g/L, 5.0 g/L in a medium similar to the previous one, does not find a statistically valid variation in the final glycerol contents.

Influence of yeast species isolated from natural fermentation media: Hansenula anomala, Saccharomyces cerevisiae, Saccharomyces aceti, Schizzosaccharomyces pombe.

Only these last yeasts have glycerol production curves very different from those of the other yeasts tested.

Influence of the mode of conduct of industrial fermentations:

By examining the manufacturing process generally followed in the industrial production of rum, we realized that glycerol appears during the aerobic growth phase of yeasts. Given the reduced richness of the medium, often less than 200 g/L of molasses or about 100 g/L of fermentable sugars, and the low rate of seeding practiced, it can be said that currently in the French West Indies, a part not negligible sugar is consumed to develop glycerol.

On the other hand, the operation of industrial installations is discontinuous. The canes brought to the distillery may be subject to pre-fermentation, with consequent production of glycerol. The glycerol level reaches 0.8 g/L on average in pipes that are poorly emptied.

Glycerol derivatives

Yeasts and bacteria can use glycerol. For these latter microorganisms, a review was conducted by Lin (1976).

Ganou and Parfait (1980) determined many species of bacteria in the flora of fermentation media leading to the various qualities of rums. As can be seen from Table II, cane juice and molasses, even when preserved, contain few germs. From the first hours of fermentation, a flora of varied origin (installations, water, environment) develops. During the course of fermentation, anaerobiosis causes a reduction in the number of species present in the medium. Lactic acid bacteria and Clostridia are mainly found. Acetobacters may appear at the end of fermentation and degrade the ethanol formed.

If sometimes the intervention is beneficial (some strains of clostridia, among others, for the production of rum aroma) most often it is detrimental to the organoleptic qualities. Acetobacters cause, for example, a detrimental increase in the level of acetic acid and ethyl acetate.

The appearance of volatile derivatives of glycerol is due, for a large part, to the activity of lactic acid bacteria, as we have observed in some distilleries. We searched in the lab, among the species of lactic acid bacteria that we had isolated, those that degraded glycerol. The tests were done aerobically and anaerobically.

Three culture media were used: M1, M2, M3.

TABLE 2

The kinds of bacteria found in fermentative environments. (+) = present, (-) = absent. The number of signs indicates the frequency. A, B and C represent the environments leading to agricultural rum, molasses rum and rum grand arôme

Under the conditions of our tests, some lactic acid bacteria use glycerol as a carbon source. Surely we could identify among them strains of leuconestoc mesenteroid. Other species also having a metabolic activity from glycerol are being identified.

Acrolein and 2propene ol 1 were found among the products formed by gas chromatography using a Tracor 560 with flame ionization detectors. The phase for the 50 foot Scotch column and 0.2 inch diameter used is carbowax 1540; the flow rate of nitrogen, carrier gas, is 3 ml/min. Temperature programming was carried out: 6 minutes at 58° C. and then an increase of 8°C. per minute up to 120°C.

The injection of 1 μL of rum can detect 1 ppm acrolein or 2propene ol 1.

A typical chromatogram is given in Figure 1.

Conclusions

In the production of rum, glycerol may be found in greater or lesser quantities depending on the mode of conduct of fermentation operations.

If the raw material (fresh juice or molasses) has not been the subject of microbial activity, in particular by yeasts, the glycerol contents will be very low.

The use of a leavening tank causes a significant concentration of glycerol from the beginning of the anaerobic phase. Schizzosaccharomyces cause the appearance of significant amounts of glycerol, which can cause problems when there is a risk of contamination by bacteria degrading this substance.

Indeed, lactic acid bacteria (leuconostoc mesenteroid type) can metabolize glycerol to lead in particular to acrolein and 2propene ol 1 found in rums with other products of negative organoleptic character.

These observations should guide the process of fermentation of raw materials to obtain a good quality rum.

BIBLIOGRAPHY

DUBOIS P., PARFAIT A., DE KIMPE J. (Mme), 1973. – Présence de dérivés de l’acroléine dans un rhum à goût anormal. Ann. Technol. Agric., 22, 131-135.

EGGSTEIN M., KUHLMANN E., 1974. – In methods of enzymatic analysis (Bergmeyer H.L.), Vol. 4, 1825-1835, « Verlag Chemie Weinheim ».

GANOU B. (Mme), PARFAIT A., 1980. – Les microorganismes de fermentation de mélasse et de jus de canne (en préparation).

LAFON M. (Mme), 1955. – Contribution à l’étude de la formation des produits secondaires de la fermentation alcoolique. Thèse de Docteur en sciences physiques, Bordeaux, Ann. Techn. Agri., 198 p.

LIN E.C., 1976, – Catabolisme du glycérol et sa régulation chez certaines bactéries. Annal Review of microbiology, vol. 30.

NORDSTROM K., 1968. – Yeast growth and glycerol formation II carbon and redox balances. J. Inst. of brewing, 74, 429.432.

OURA. E., 1977. – Reaction products of yeasts fermentations. Process Biochemistry, 12, 19-35.

SABIN G., PARFAIT A., 1975. — Les fermentations traditionnelles de mélasse et de jus de canne aux Antilles Françaises, lnd. Agric. Alim., 92, 27-34.

SER JAK W.C., DAY W.H., VANLANEN J. M., BORUFF C.S., 1954. – Acrolein production by bacteria found in distillary grain mashes, Applied Microbiology, 2, 14-20.

DE SMEDT P., LIDDLE P.A.P., 1976. – Présence d’alcool allylique (2propène  ol 1) et dérivés dans les eaux-de-vie. Ind. Alim. Agric., 93, .41-43.

WARCOLLIER G., LE MOAL. A., 1932. – Présence accidentelle d’acroléine dans l’eau-de-vie de cidre. C.R. Acad. Science, 194, 394.

Ethyl Esters Of Higher Fatty Acids Of Rhums

Sponsor my distilling work simply by sharing the artisan workshop of the Bostonapothecary on social media. Copy, Paste, Share, Support!

Parfait A., Namory M., Dubois P., 1972. Les esters éthyliques des acides gras supérieurs des rhums. Annales de Technologie Agricoles 21, 2, 199–210.

ETHYL ESTERS OF HIGHER FATTY ACIDS OF RHUMS

A. PARFAIT, M. NAMORY and P. DUBOIS *

Station de Technologie végétale, I. N. R. A.,
Petit-Bourg (Guadeloupe)
*Station de Technologic des Produite vegetaux, I. N. R. A.,
21034 Dijon Cedes

Summary

Rums of good quality, especially in ethyl esters, generally have high fatty acids with a high content of volatile esters, and particularly of ethyl esters of higher fatty acids (from C8 to C16). These esters are by-products of alcoholic fermentation, such as higher alcohols, and behave like them during continuous distillation.

The levels of ethyl esters of the higher fatty acids are higher when the distillation is done on the lees, when cane wax is added to the must before fermentation and by selection of a species, or even of a strain, of yeast.

The ethyl ester contents of the distillate fatty acids were three times higher with Saccharomyces cerevisiae S. 132 than with Saccharomyces cerevisiae Berlin II. The highest content was obtained with a strain of Schizosaccharomyces Pombe yeast from the sugar cane regions.

It has not been possible to establish definitively a correlation between the fatty acid composition of the lipids of the yeast cell and the ethyl esters produced.

Key words: rums, ethyl esters, higher fatty acids, distillation.

I- INTRODUCTION

The eaux-de-vie can be considered as hydroalcoholic solutions of a “non alcohol” which characterizes them and that the chemical analysis makes it possible to separate in dry extract, acids, aldehydes, esters and higher alcohols, These analyzes can be completed by olfactory observations on isolated fractions by distillation. Finally, much finer separations can be obtained by gas chromatography for the determination of volatile constituents and by other chromatographic methods for the study of nonvolatile compounds.

In the case of rums, there may be a relationship between their quality and their ester content (KERVEGANT, 1946) and, in spite of many exceptions, it seems that high ester levels characterize the most aromatic rums. Observations made after fractional distillation even suggest that heavy esters have the greatest influence on the aroma of these eaux-de-vie, as is the case with whiskeys (SALO et al., 1972). The technology of rums should therefore be able to take advantage of recent studies on the formation of esters by yeasts during the fermentation of wines and beers.

A.—Mechanism for the formation of esters

PEYNAUD (1956) has shown that the levels of ethyl acetate in fermented media depend on the yeast species, and that they are always higher than those predicted by the calculation from chemical equilibrium reactions.

According to NORDSTRÖM (1964), the esters are formed by alcoholysis of the acyl-coenzymes A according to the reaction

and their formation depends on the contents of acyl-Co A and alcohols (RAINBOW, 1970) The alcohols react all the better as they are primary, with a linear chain and of lower molecular weight. Since ethyl alcohol is the most abundant, the esters formed are mainly ethyl esters.
On their side, acyl-Co A have three modes of formation.

Activation of fatty acids in the presence of ATP.

In view of the very small quantities of free fatty acids in fermented media, it seems that this reaction can play only a minor role.

Oxidative decarboxylation of α-cetanol acids.

This reaction is thought to be responsible for most of the acetyl-Co A, by oxidative decarboxylation of pyruvic acid. The other α-keto acids, that is to say certain intermediates of the metabolism of sugars and of amino acids, are present in much smaller quantities than pyruvic acid, and very few esters of the corresponding acids are formed. (propionic, isobutyric, methyl-2 and 3-methyl-butyric).

Reaction between an acyt-Co A and malonyl-Co A.

This reaction, which leads to the formation of the fatty acids of the lipids of constitution of the yeast, is also at the origin of the ethyl esters of linear fatty acids with an even number of carbon atoms.

Ester formation is related to yeast growth, as is that of higher alcohols and the formation of higher fatty acid esters is more particularly related to lipid metabolism.

It is therefore, like that of lipids, favored by the presence of pantothenic acid, as constituent of coenzyme A, and of the biotin which participates in the carboxylation of acetyl-Co A in malonyl-Co A, and which therefore, competes with the formation of ethyl acetate.

Factors that limit the development of yeasts have an inhibitory role. This is particularly the case of linear fatty acids having 6 to 10 carbon atoms which are toxic to yeasts.

B.— Fermentations in rhummeries

We know imperfectly the flora that develops in the environments put in fermentation to produce the different types of rums. HARRISSON and GRAHAM (1970) point out, in a development, that the budding yeasts gradually replaced, in Jamaica, a fission yeast, Schizosaccharomyces melacei, which was dominant at the beginning of the century.

Overall, fission yeasts are preferable to budding yeasts, in part because they promote the development of butyric bacteria (Clostridium saccharobulyricum, in particular) that produce very large quantities of esters. These fission yeasts are particularly abundant in the flora used for the elaboration of “grand arôme” rums.

It is also possible that yeasts of the genus Torulopsis play an important role in the formation of esters from sugars.

In the French Antilles, Saccharomyces cerevisiae is the main agent of fermentations. Other yeasts are present, including Pichia, Hansenula, Candida and Schizosaccharomyces. Their role is difficult to assess in practice.

C.— Role of distillation

Esters are poorly soluble in water and behave like head products in low alcohol environments. They behave, at the same time, as bottoms in the distillation columns when the alcoholic degree reaches values ​​of the order of 50 to 60 ° GL. Only ethyl acetate is always in the heads. Butyrate and ethyl hexanoate distill substantially at the same time as ethanol. The ethyl esters of acids that have 8 carbon atoms and more distillate after ethanol and it is these acids that we consider here as superior.

The contents of the rums in the ethyl esters of the higher fatty acids are therefore related to the alcoholic degrees to which they are distilled in the columns. The higher this degree, the poorer the rum obtained in these esters. It is interesting to note that the behavior of higher alcohols is quite similar to that of heavy esters.

In any case, the analytical results obtained on rums, and in particular the quantitative results obtained by LIEBICH et al. (1970) (Table I) shows that the main esters are the ethyl esters of fatty acids number by carbon atoms. Ethyl acetate and butyrate dominate among the light esters, caprate and palmitate among the heavy esters. Certain unsaturated acid esters are also present, but in smaller proportions.

Table I
Ethyl esters reported in rums

After having measured the ethyl esters of higher fatty acids in commercial rums, various factors have been studied that may affect the levels of these constituents in rums: presence of yeasts during the distillation fermentation in the presence of cane wax fermentation by various species of yeast. These different points were completed by the analysis of lipids of yeast constitution.

II- MATERIAL AND METHODS

A.— Culture media

Two media were used, one is based on cane molasses, the other synthetic.

These solutions are brought to pH = 5 with sulfuric acid and sterilized by treatment at 110 ° C. for 35 minutes.

B.— Yeast uses

Apart from Schizosaccharomyces pombe, which was isolated from a fermentation of cane juice medium, the other species came from the Dijon Plant Products Technology Station collection: Saccharomyces cerevisiae strains Berlin II and S. 132, Pichia membranaefaciene, Hansenula anomala and Candida krusei. These yeasts are those which have been reported as participating in the fermentation of musts in rhummeries.

With a young culture of yeasts, flasks containing 100 ml of liquid Wickerham medium are inoculated with malt. After about 24 hours at 28 ° C, in stirred medium, the yeasts are collected by centrifugation, then they are rinsed twice with saline water. All media are inoculated so that they initially contain 5 · 10 ^ 6 yeasts per ml. A magnetic bar agitates the first day and fermentation lasts 3 to 4 days at 28 ° C.

C.— Analysis made on distillates

The apparatus to be distilled is made of glass and includes a balloon, an electric heater, a column of Vigreux of 50 cm of height and a refrigerant.

Ethyl esters of fatty acids of 8 to 16 carbon atoms are not very polar and their most selective solvent must itself be polar. We chose pentane.

A test portion of 100 ml of distillate at 50 ° GL is stirred vigorously with 50 ml of pentane. The addition of 100 ml of water causes an immediate demixtion without emulsion formation. The organic phase is dried over anhydrous sodium sulphate and brought to a tenth of a milliliter by distillation. Two microliters are injected into a Perkin-Elmer model 880 chromatograph under the following conditions: column filled with Chromosorb G 80/100 mesh impregnated with OV 17 at 5 p. 100, length 4 meters, diameter 3 mm. Nitrogen flow 25 ml / min. Temperature program of the injection from 160 to 240 ° C at 2 ° C per minute. Since the rums contain only traces of ethyl pelargonate, this analysis is made quantitative by the addition of one milliliter of an alcoholic solution of this ester at 1 mg / ml to the 100 ml of distillate used. Previous tests performed on synthetic solutions showed that the relative errors were less than 5 percent. The exact nature of the esters was verified in the chromatographic conditions, but in coupling with a Varian *** type CH 5 mass spectrometer (250° C source, 70 eV electron energy). All these ethyl esters are characterized by a rearrangement peak for m / e = 88,

and by their molecular peaks. Mass spectrometry also makes it possible to observe the absence of important interferences.

D.— Analyses faitee sur les levures

After fermentation, the yeasts are separated by centrifugation (10,000 g). They are twice washed with physiological water, and then harvested at the bottom of the tubes using a spatula. At weighing of the wet mass, the dry matter content is determined on an aliquot part. [aliquot was a guess. The scanning is cutting off the edge for this page].

The total lipids of the yeasts are determined by the method of KAHANE and ROUS (1961) and then saponified by the alcoholic potash. Unsaponifiable matter is extracted with petroleum ether. After acidification, the fatty acids are extracted with the same solvent, then they are esterified with hydrochloric methanol and analyzed by gas chromatography on an impregnated column [guess] of diethylene glycol succinate (impregnation rate 15%). 3 meters, inside diameter 3 mm, Chromosorb G 80/1000 mesh, temperature 190 ° C.

E.— Autres dosages

The yeasts are counted with a cell count on a possible dilution of the medium. The reducing sugars are dosed, after acid hydrolysis, by the method of Bertrand. Finally, the volatile acids are determined after entrainment by steam. [I think I translated that last part correctly.]

III. — RESULTS

A.— Levels of ethyl esters of the higher fatty acids of commercial rums

The contents of these esters of five rums were compared: two agricultural rums obtained from cane juice in a traditional factory where fermentations are most often spontaneous, and three rums obtained from industrial rum distillates at 64 ° GL, a light rum distilled at 94 ° GL, and a rum “grand arôme” distilled at 63 ° GL as industrial rum, but obtained by a fermentation procedure that uses a starter with yeasts of the genus Schizosaccharomyces and bacteria.

The results obtained are shown in Table 2.
The first three rums have very similar contents in these esters, light rum contains only traces, the most abundant being the *** of ethyl whose content is of the order of 0.05 mg / liter of pure alcohol. The numbers obtained for the rum “grand arome” are much weaker than were expected. This rum has a very low content in total esters (about 2 g / liter of pure alcohol).

Table 2

Ethyl esters of various commercial rums
(in mg per liter of pure alcohol)

B.— Role of yeasts during distillation

The synthetic medium and the molasses-based medium were used with yeast Saccharomyces cerevisiae Berlin II. In each test, four liters of medium are prepared and fermented, then they are divided into two equal parts, one of which is centrifuged before distillation to eliminate the yeasts.

The results reported in Table 3 show that distillation in the presence of yeasts leads to a significant gain in esters. These compounds are poorly soluble in low alcohol environments and are likely to be absorbed on the surface of yeasts and suspended particles.

TABLE 3

Role des levures et de la cire de canne sur les teneurs des distillats en esters ethyliques des acides gras superieure
(n-C8 n-C16 en mg par litre d’alcool pur)

C.— Role of cane wax

The wax is the richest part of the higher fatty acids of the cane (*** according to MARTIN and JUNIPER, 1970), and it was interesting to see what could be its influence.

It was added in the form of an emulsion at a dose of 0.300 g per 4 liters of medium. The results (Table 3) show that this addition of wax allows a medium based on cane molasses to double the levels of distilled ethyl esters of fatty acids with 8 and 10 carbon atoms which are among the interesting ones on the olfactory plane ( SALO et al., 1972).

The synthetic media are incompletely fermented and the results obtained are unusable.

D.- Role of the yeast species

EL SHEHATA (1960) has shown that molasses musts are fermented, in practice, by the following yeast species: Saccharomyces cerevisiae, Schizosaccharomyces pombe, Hansenula anomala. Pichia membranaefaciene and Candida krusei. The first two ferment well in anaerobic environment, the last two do not ferment sucrose.

TABLE 4

Ethyl esters of distillates obtained with different yeast species
(in mg per liter of pure alcohol)

Yeast species used:
Pichia membranacfaciens (P. m.), Hansenula anomala (H. a.), Schizosaccharomyces pombe (S. p), Candida krusei (C. k.), Saccharomyces cerevisiae S. 132 (S. c. 132).

We have fermented, under the conditions defined above, five mediums based on molasses with respectively each of the following yeasts:

– Pichia membranaefaciens (P. m.)
– Hansenula anomala (H. a.)
– Schizosaccharomyces pombe (S. p.)
– Candida krusei (C. k.)
– Saccharomyces cerevisiae S. 132 (S. c. 132).

After fermentation, the media are distilled in the presence of yeasts. The results are summarized in Table 4.

Some media have been incompletely fermented because Pichia and Candida do not ferment sucrose.

E.- Fatty acid content of yeasts

The determinations were made on yeasts derived from fermented media based on molasses similar to the preceding ones, but, to promote the multiplication of yeasts, the stirring period was increased to 48 hours instead of 24. Tables 5 and 6 report on the results obtained during various determinations.

TABLE 5

Data on the fermentation by different species of yeasts in molasses medium

TABLE 6

Comparative composition of lipids of various yeast species

There appears to be some correlation between the amount of ethyl esters of the higher fatty acids produced by these yeasts and their levels of saturated fatty acids. However, the methods used do not make it possible to know if the fatty acids doses were glycerol related in the lipids of constitution, or if they were in the form of ethyl esters and associated with the yeast walls.

IV.— DISCUSSION

The levels of ethyl esters of the higher fatty acids of commercial rums are close to those we were expecting to find except for the “grand arôme” rum. On rum of this type Liebich et al. (1970) indicate contents of the order of 170 mg per liter of pure alcohol, thus of much higher contents and which are similar to those obtained when working with Schizosaccharomyces pombe. The poorly defined origin of these products makes it possible to make only findings.

The presence of yeasts during the distillation makes it possible to obtain richer eaux-de-vie in esters. This confirms the work of GUYMON and CROWELL (1969) and partially explains the preference of practitioners for the lees distillation method.

GUYMON and CROWELL (1969) assume that, during continuous distillations, the fatty acids released by the yeasts are esterified with ethanol on the first plats of the column. The results reported here do not seem to be explained in this way since the distillations were performed, in the laboratory, discontinuously and that therefore the higher fatty acids could not be found in the free state presence of a high concentration of ethanol. It seems more probable that esters were linked to yeasts, either on their wall or in their cells and that they were released by heating.

The results concerning the addition of wax are more difficult to interpret since its composition is poorly known. It is known to contain a small amount of free fatty acids with a very high carbon number, which are yeast growth activators, but its biotin and pantothenic acid contents are not known in industrial practice. It will be interesting to know if the simple addition of palmitic acid would not have effect, palmitic acid being the main fatty acid of the lipids of yeast.

Finally, there were important differences between one yeast species and another, even from one strain to another within the same species. Under the same conditions, Saccharomyces cerevisiae Berlin II produced 36.5 mg of these esters per liter of pure alcohol (Table 3) while Saccharomyces cerevisiae S. produced 114 (Table 4).

The highest content was obtained with Schizosaccharomyces pombe, which is the dominant species in the flora of wines prepared for the production of “grand arôme” rum.

V.— CONCLUSION

Although their mixture can not be at the origin of the characteristic aroma of the rums, it seems probable that the ethyl esters of the volatile fatty acids participate in their qualities. Therefore, it was useful to specify the conditions allows rums rich in these constituents.

The most important factor is doubtless the distillation and alcoholic degree to which the alcohols are obtained continuously. The higher the rectification rate, the lower the ester and higher alcohol contents.

On the other hand, three factors seem to be able to be used to increase the levels of esters while keeping low contents of higher alcohols: the addition of wax, the distillation of the turbid substances and the selection of a species, or even of a yeast strain.

Received for publication in October 1972.

SUMMARY

ETHYL ESTERS OF THE RUM HIGHER FATTY ACIDS

Good quality rums have generally a high content of volatile esters and especially of ethyl esters of higher fatty acids (n-C8, to n-C16). These esters are secondary products of alcoholic fermentation, like higher alcohols,and behave like them during a continuous distillation process.

The quality of rums should be improved using our recent knowledges on esters production by yeasts in beer and wine.

Higher contents of ethyl esters of higher fatty acids can be obtained when the yeasts are not removed from the wines before distillation, when sugar cane wax is added to the must before fermentation and when a yeast species, and even a yeast strain, is selected.

The higher fatty acid ethyl ester contents of distillates were three times higher with Saccharomyces cerevisiae S. 132 than with Saccharomyces cerevisiae Berlin II. The highest content was obtained with a strain of Schizosaccharomyces pombe, a native yeast of sugar cane growing Countries.

A correlation between the fatty acids composition of the lipids of the yeasts cells and the ethyl esters produced could not be conclusively established.

BIBLIOGRAPHY

BARAUD J.,MAURICE A., 1963. Les alcools et esters des eaux-de-vie de canne et de pomme. Ind. aliment. agric., (1), 3-7.

EL SHEHATA A. M., 1960. Yeasts isolated from sugar cane and its juice during the production of Aguardente de Cana. Appl. Microbial., (8), 73-75.

GUYMON J. F., CROWELL E. A., 1969. Gas chromatographic determination of ethyl esters of fatty acids in brandy or wine distillates. Amer. J. Enol. Vitic., 20 (2), 76-85.

HARRISSON J. S., GRAHAM J. C. J., 1970. In The Yeasts, vol. 3, Acad. Press, London.

KAHANE E., Rous S., 1961. Nouvelle methode d’extraction des lipides, in Enzymes of lipid metabolism 82-90, Pergamon Press, Oxford.

KERVEGANT D., 1946. Rhums et eaux-de-vie de canne. Les Editions du Golfe, Vannes.

LIEBICH H. M., KOENIG W. A., BAYER E. 1970. Analysis of the flavor of rum by gas liquid chromatography and mass spectrometry. J. Chromatogr. Sci., 8 (9), 527-533.

MAARSE H., ten NOEVER DE BRAUW M. C., 1966. The analysis of volatile components of Jamaica rum. J. Food Sci., 31, 951-955.

MARTIN J. T., JUNIPER B. E, 1970. The cuticles of plants. Ed. Arnold Publishers Ltd, Edinburgh.

NORDSTRÖM K., 1964. Studies on the formation of volatile esters in fermentation with brewer’s yeast. Svensk Kemisk Tidskrft, 76 (9), 510-543.

PEYNAUD E., 1956. Sur la formation d’acetate d’ethyle par les levures du vin. Industr. aliment. agric. 73 (4), 253-256.

RAINBOW C., 1970. Brewer’s yeasts, in The yeasts, vol. 3, Acad. Press, London.

STEVENS  R., 1965. Gas chromatographic identification of ethyl ester of fatty acids in domestic and imported rums. J. Ass. off. agric. Chem., 48 (4), 802-805.

SALO P., NYKANEN L., SUOMALAINEN H., 1972. Odor thresholds and relative intensities of volatile aroma components in an artificial beverage imitating whisky. J. Food Sci., 37 (3), 394-398.

SUOMALAINEN H., PUPUTTI E., NYKANEN L., 1968. Composition of the aroma in some brands of whisky and rum analyzed by customary methods and by gas chromatography. Kemian Teollisuus 25 (5), 399-404.