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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 Some of the techniques in here would become quickly outdated such as measuring free volatile acidity as formic instead of acetic.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.)
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.