Presence Of Acrolein Derivatives In A Rum Of Abnormal Taste

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

Dubois P., Parfait A., Dekimpe J., 1973. Présence de dérivés de l’acroléine dans un rhum à goût anormal. Annales de Technologie Agricoles 22, 2, 131–135.

This is part of a series where French language papers related to the production of fine rums are translated to help emerging industry and celebrate the work of great scientists. I translated everything with google then did a little minor poetic rendering. What is interesting is that the end has abstracts in English, Spanish, and Italian, and that much of the bibliography comes from the whiskey industry illustrating that the faults they are studying overlap.

Station de Technologie des Produits végétaux,
Centre de Recherches, I. N. R. A.,
B.V. 1540, 21034 Dijon Cedex
* Station de Technologie des Produits végétaux, I. N. R. A.,
97.170 Petit-Bourg

A rum with an abnormal taste was analyzed by gas chromatography and mass spectrometry. Two compounds were identified as 3-ethoxypropanal and 1,1,3-triethoxypropane, in addition to ethanol of acrolein. These compounds have already been found in “peppered” whiskeys whose abnormal taste also comes from the formation of acrolein during fermentation.

Key words: rum, acrolein, aroma, gas chromatography, mass spectrometry.

The presence of an abnormal taste was reported in some freshly distilled rums. Their pungent smell disappears through aeration, but at the end of tasting we can perceive a taste that tasters have described as “phenolic” or “pharmaceutical”. This is what distillers call the taste of the still, which disappears after a longer or shorter time.

Material and Methods

A 500 ml sample of aerated peppered rum, freshly distilled and shipped to Martinique in a glass bottle, was redistilled until almost complete removal of the ethanol in a glass apparatus with a Vigreux column of 5o cm. The distillate, rediluted with an equal volume of water, had a normal taste, and the analysis focused on the residue.

By extraction with diethyl ether and total evaporation of this solvent, we obtained a few tenths of a ml of a concentrate having a strong smell of rum, but of unpleasant taste, even after dilution in a alcoholic-water solution at 50 ° GL. This concentrate was analyzed in gas chromatography-mass spectrometer coupling under the conditions indicated in Table I.

The beginning of the chromatogram obtained is shown in FIG. I. Two unusual peaks surround the peak of 2-methylbutanol and 3-methylbutanol which are not separated on the liquid phase used. The mass spectrum of compound A, which is indicated in FIG. 2, is in good agreement with that published by Stenhagen et al. (I969) for 3-ethoxypropanal. The peaks M + —1 (m/e = 101) and M+—44 (m/e = 58) are characteristic of aliphatic aldehydes, although here the hydrogen rearrangement leads to the formation of the peak M+— 44 is done by a way a little different from that which is conventional, because of the presence of oxygen in the gamma position. The peak M+—28 (m/e = 74) corresponds to the loss of one molecule of ethylene and is nothing other than the parent peak of 3-hydroxypropanal (Figure 3). This compound breaks up in turn to give the ions at m/e = 73 (loss of a hydrogen), at m/e = 45 (+CH2-CH2-OH) and at m/e = 31 (CH2 = +OH). In the case of 2-ethoxypropanal, the peak at m/e = 45 should logically be more intense than the peak at m/e = 31.

Compound B (Figure 1) is the acetal of this aldehyde: triethoxy-1, 1,3 propane. The retention volumes and the mass spectra of the two compounds were verified by analysis of the corresponding synthetic products.

Discussion and Conclusion
Maarse and ten Noever de brauw (1966) reported the presence of 2-ethoxypropanal in rums, but it is more likely that it is 3-ethoxy propanal as indicated by Kahn et al. (1968, 1969) in the case of so-called “peppered” whiskeys. This ethoxy-propanal is formed by the addition of ethanol to the double bond of acrolein (Kahn, Laroe and Conner, 1968), during which the ethoxy radical is attached to the carbon atom having the lowest electron density, that is to say in position 3 in the case of acrolein. There is every reason to believe that this reaction occurs during distillation, when acrolein is in the presence of a high concentration of ethanol and at high temperature.

The production of acrolein has been studied during the alcoholic fermentation of wines since Pasteur showed, in 1886, that it was formed at the expense of glycerol, because of the metabolic activity of certain facultative anaerobic bacteria. More recently, this problem has been studied in the case of “peppered” whiskeys by Mills, Baugh and Conner (1954) and by Serjak et al. (1954).

However, neither 3-ethoxypropanal nor triethoxy-1,3 propane appears to have the abnormal taste of the rum studied, even after dilution of these products in ethanol at 5o°GL. Now, it suffices to distill a mixture of water, ethanol and acrolein, to aerate the distillate and to dilute it with an equal volume of water to obtain the desired abnormal taste.

Thus, the abnormal taste observed, on the one hand, and the presence of 3-ethoxypropanal and 1,1,3-triethoxy propane, on the other hand, are both related to the presence of acrolein in the base wine. As for acrolein remaining free, it must be found in the distillation heads or have been removed from the distillate during aeration.

Other derivatives of acrolein may be present, but they could not be highlighted either by the detector of the chromatograph, or olfactory at the column outlet.

Received for publication in May 1973.

A rum, which presented an off-flavour, has been analysed by gas chromatography and mass spectrometry. Two compounds were identified to 3-ethoxy propanal and 1,1,3-triethoxy propane, which are addition products of ethanol on acrolein. These compounds have already been identified in peppery ) whiskies, whose off-flavour originates also from the formation of acrolein during the fermentation. [original English language abstract from the end]

Un ron que presentaba un sabor anormal ha sido sometido a análisis por cromatografía en fase gaseosa y espectrometría de masa. Han sido identificados dos compuestos, el etoxi-3propanal y el trietoxi-1,1, 3 propano, productos de adición del etanol sobre la acroleina. Estos compuestos han sido encontrados ya en los whiskis « pimentados » cuyo sabor anormal procede también de la formación de la acroleina durante la fermentación.

RIASSUINTO [and now in Italian!]
Un rum con sapore anormale è stato analizzato mediante gas-cromatografia e spettrometria
di massa. Si son trovati due composti : etossi-3 propanale e trietossi-I, I, 3 propano, prodotti d’addizione dell’ etanolo sull’acroleina. Questi composti sono stati già trovati in whisky «pepati) il cui sapore anormale è dovuto egualmente alla formazione d’acroleina durante la fermentaZIOIle.

KAHN J. H., LAROE E. G., CONNER H. A., 1968. Whiskey composition : identification of components by single-pass gas chromatograph-mass spectrometry. J. Food Sci., 33, 395-4oo.

KAHN J. H., SHIPLEY P. A., LAROE E. G., CoNNER H. A., IQ69. Whiskey composition : identification of additional components by gas chromatography-mass spectrometry. J. Food Sci., 34, 587-591.

MAARSE. H., ten. No EVER DE BRAUW M. C., 1966. The analysis of volatile components of Jamaica rum. J. Food Sci., 31 (6), 95 I-955.

MILLS. D. E., BAUGH. W. D., CONNER H. A., I954. Studies on the formation of acrolein in distillery mashes. Appl. Microbiol., 2 (II), 9-13.

SERJAK W. C., DAY W. H., VAN LANEN J. M., Boruff C. S., 1954. Acrolein production by bacteria found in distillery grain mashes. Appl. Microbiol., 2 (1), 14-20.
STENHAGEN E., ABRAHAMSSON S., Mc LAFFERTY F. W., editors, 1969. Atlas of mass spectral data.
Intersc. Publishers, 1, 275.

2016 Retrospective

Being December, it is time for the year end retrospective. Like usual, I felt like I didn’t accomplish much, but I did write about 20 posts with some containing distilled spirits’ most significant historic discoveries for the year (examining Arroyo) and others containing distilled spirits’ most progressive ideas (congeners derived from glycosides).

I have put a lot of beverage work on hold to become a design world darling and start the Houghton Street Foundry (IG: @houghtonstfoundry) which makes exquisite door hardware and offers architectural machining services. I have ghost written a few products for small distilleries with one being the hottest off premise specialty product in New England, though I actually think I designed it last calendar year. My beverage pace has slowed down, but I’m still holding significant technique and history secrets from the industry (to punish you all!).

The year started with Rum Comparatively: Understanding Anything Goes and explains how production compares to other spirits categories and why rum is the most progressive spirit with unique production templates that other categories do not use.

Aggressive collecting led me to Excise Anecdotes from Arrack Country which tells some of the most breath taking (and heart breaking) distilling stories ever recorded. It also ends with a beautiful discovery and meditation on terroir.

There is a ton of WTF? in Rum, Mitogenic Radiation & The Bio-photon. Brilliant Science writer, Adam Rogers, was cool enough to spend time weighing in so I had a lot of fun with the post. It does show that Rafael Arroyo was a far out thinker with an ear to the ground and yet again reinforces the idea of rum as the most progressive spirit. Nearly a century of science later not much is clarified.

This was particularly important to me because I’ve long been a champion of the rums of Cape Verde. In Cape Verde and Sugar Cane Juice Rum Categories I apply explanations from Arroyo to my favorite distilling tradition and explain the origins of their distinct aromas. There are so many supposed rum experts and they are still avoiding Cape Verde and the island of Madeira. Berry’s or Plantations rums, where you at? I’ll connect you to Cape Verde’s most brilliant distillery.

Here I describe my plan for discovering a new generation of champion rum yeasts: Team Pombe and the Yeast Olympiad. So far I haven’t been able to get it off the ground because of a lack of interest from the small distilleries in my circle (and the very expensive process). I will likely finance and execute the ideas by myself and I’m not afraid if it takes quick a few years. No one else seems to be too interested in this territory.

Rum, Osmotolerance and the Lash was so much more than a cute title and looks at forces that shape microbial communities, especially when trying to cultivate a dominant Pombe fermentation.

I had heard murmers of these ideas so long ago from Ed Hamilton so I decided to tackle them in Aroma Breakage and Rum Design. Arroyo as usual was on top of everything. Some new producers like Maggie Campbell of Privateer are known to be very much hip to this and weave the ideas in production.

Ageing, Accelerated Ageing, & Élevage ==> Lies, Damn Lies & Statistics This was my look at Arroyo’s progressive musing on the aging topic. I think this was before I read UC Davis great, Vernon Singleton’s, legendary paper which I probably should have given its own post (2017!)

Narrative of the 1975 Rum Symposium

Say it with me:
Rum is the most progressive spirits category.
Rum has the most researched spirits production.
There is nothing finer than rum as we make it.

There is so much good stuff in the symposium.

I had never done a spirits review before and of course I did it on my own terms. This post, Spirits Review: Mezan XO Jamaica Rum, also ends up with a challenge of drinking 10 ounces in one sitting to test a theory many are anecdotally validating. I also drop one of the most progressive ideas in all distilling and introduce a new congener category. Its not my fault if people cannot keep up.


Before I left to run a popup in Province Town this summer, I introduced For Sale: Large Bottle Bottler. This tool is particularly awesome but not for everyone and I don’t push it. Some bars are killing it with my bottlers and I am in some of the world’s top programs while other notable programs cannot assemble a team that can handle the tasks. A lot of a sales go to winemakers doing research projects for their own product development. I owe you all a new post on kegging to show you’ve all been doing it so so wrong.

In the frustration of the election and inspired by blog hero George Lakoff, I penned Public foundations for Private Spirits Companies. The post is a meditation on how private companies get built on a foundation of public research and how we are starting to forget that. A new generation of distilleries is popping up that often flounders with the technical aspects of product development because they do not seek out any of the amazing research that came before them. Most distillers are in disbelief the research exists when I introduce it to them. This rickety blog is the largest source of advanced educational material for the new American distilling industry which is approaching a billion dollars in revenue and quite a few hundred million in investment.


Here I introduce the Alaska Ice Crusher and describe a stunning restored version produced by a new friend. I’ve used Alaskas for a quite a few years and lately have been seeing them popping up in finer bars. They have become a Boston bar scene thing and collectively we own quite a few.

In A Few Papers For The Industrious I take a break from foundry work to read from papers that Rex sent in which I’d been hoping to come across for a few years now. Having gotten in the mood, I also shared up some delicious snippets from the archives of rum arcana.

Patrick Neilson Tells of Rum (Like No Other), 1871 This was easily my favorite piece of the entire years with its companion article J.S. Tells of Rum, Jamaica 1871. These papers kick off the fine rum era and are full of the choicest opinions on things like skimmings that many of us have heard of but don’t quite understand.

This piece was short and fun and simply shows that even as far back as 1885, which is a few life times out from the birth of the term, people were into tracking down etymologies: Etymology of the Word Rum by Darnell Davis (1885).

This is only for nerds and if you’re short on time and need to triage your reading, skip this, Occurance of Lime-Incrustations in Rum Stills (1903), and the next post, Scientific Control of a Rum Distillery by F. I. Scard.

As I collect papers, a genre of writings is emerging and this is an enjoyable example from a seldom described island. W. M. Miller Tells of Rum in Guyana for Timehri (1890)


We ended the year with the Return of the Champagne Bottle Manifold where I mastered single point threading on the manual engine lathe and started cutting the proprietary 19/32-18 threads myself to improve the design. My design over the years has evolved to be really spectacular, but they didn’t really catch on because programs didn’t want to pay for them and those that did had them frequently stolen. The most serious users ended up being Champagne sales reps.

Who knows what next year will bring. Sadly for the Bostonapothecary blog, my focus will be in the workshop. Ask questions or challenge me and I may sit down and post.


Narrative of the 1975 Rum Symposium

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

Say it with me:
Rum is the most progressive spirits category.
Rum has the most researched spirits production.
There is nothing finer than rum as we make it.

As usual another cache of forgotten rum papers showed up that paints a narrative of rum advancement mid 19th century that is seldom looked at. It seems to be far easier to study much older periods. This collection of articles was assembled for a symposium held in the West Indies.

I’m having a busy week between the machine shop and the restaurant so I’ll just put this out there then maybe follow up on it later.

The Analytical identification of rum / R. J. Mesley, D. B. Lisle, C. P. Richards and D. F. Wardleworth
Set Level: Annales de Technologie Agricole. N.º 3-4, vol. 24 (1975), p. 361-370

This paper is part of the beginning of the chromatography era and of course rum led the way. One reason spirits finger printing was important was because of all the trade rules governing the movement of rum. If you could confidently identify a rum, there would be less chance of theft (because it had to turn back up again) or illegal aliens and rum border jumpers moving around. All analysis was conducted in a “revenue protection laboratory”. For a long time this analysis did not help advance production but was merely for revenue protection.

Formation of acetals in run : a kinetic study / K. Misselhorn
Set Level: Annales de Technologie Agricole. N.º 3-4, vol. 24 (1975), p. 371-381

The chemistry in this paper is kind of heavy. I guess the amount of acetals should be at a predictable level when at equilibrium with a given amount of aldehydes, but that isn’t always the case because of the formation of semi-acetals. The paper notes that there is dispute on the organoleptic importance of acetals. Some downplay their importance while others say some are very important to flavor. I think Piggot wrote about their importance. I don’t know enough about them.

The rum pilot plant of the agricultural experiment station of the university of Puerto Rico : past, present, future / A. E. Molini
Set Level: Annales de Technologie Agricole. N.º 3-4, vol. 24 (1975), p. 391-396

This summary of the Pilot Plant is particularly important and some of its intentions are revealed. It also helps contextualize Arroyo whom the torch was passed from. Arroyo produced a lot of “leads” for further investigation, but I don’t think the Puerto Rican industry, with its massive responsibilities (that we typically fail to recognize), were interested in making complex, fine, full bodied, Jamaica-type rums. I think their work paved the way for a lot of the rums that would give the category a bad name. There were investigations of super clean ferments using antibiotics and chemical additives, investigations of very high alcohol ferments with intense optimization of fermentation variables. At the same time there research made the industry very environmentally friendly.

As we will see in another paper, there was intense automation and optimization of high proof distillation. The paper has some brief summaries of their achievements and a unique one is that of ageing where they realize that even with all their scientific resources, there is no substitute for natural ageing in the barrel.

This paper is well worth reading and I do have the annotated bibliography of the Pilot Plant which I will eventually start collecting.

Possibilities of utilization of butyric acid bacteria for rum making / S. Nemoto
Set Level: Annales de Technologie Agricole. N.º 3-4, vol. 24 (1975), p. 397-410

Wildly interesting, but sadly a very poor scanning. Arroyo’s ideas seem to have made it all the way to Japan and the Japanese made super full bodied rums even though they weren’t rum drinkers! They made confections! They were even investigating Pombe yeasts! “Furthermore, Japanese do not drink rum so much. […] After the Second World War, goods for daily use were insufficient and their qualities were poor. Materials of confectionary, such as butter and wheat flour, were not an exception. Heavy rum was used in order to improve the taste and flavor of cake made from those bad materials. Thus, rum has been developed not as a drink, but as a confectionary use, and in Japan heavy rum was wanted. […] We had to study rum making under very different conditions from West India.”

The world is full of lost rums.

What is to be found in literature about rum production that is more than 300 years old? / H. Olbrich
Set Level: Annales de Technologie Agricole. N.º 3-4, vol. 24 (1975), p. 411-420

This paper is of wild importance and amasses a bibliography of 150 sources, much of which are in German. I find myself sympathizing with the author a lot. And he hypes my home boy, Mr. Motherfucking Pombe, Percival Greig.

“It was not until a century later that the Englishman Percival H. Greig, 1893-1895, followed with systematic results on rum manufacture. Before going to Jamaica, Greig acquainted himself with microbiological procedures, aided by the Danish scholars Hansen and Jorgensen in Copenhagen. In 1895 however, his interest in publishing any work of his was brought to a close with three papers. Greig himself had become a rum manufacturer.”

So I am acquainting myself with microbiology procedures and walking a similar path.

“In 1936, Greig’s work was still reviewed to a substantial degree in an extensive paper [where is this paper?!], as the basic position of science regarding rum manufacture. So no abundant material is to be found in literature about rum manufacture until nearly the middle of our century. In the last decades, numerous circumstances have influenced both production and market development, as well as yielding some scientific papers. It is an irrefutable fact that a library is cheaper than a laboratory [emphasis mine] 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. For a sequel to the examination of literature work, which is sometimes unjustly underestimated, American atomic research offers an example which should be a warning; at an expenditure of vast sums of money, problems were supposedly dealt with, for which complete results were already to be partly found in literature.”

That language! And did he just compare rum research to nuclear research, fucking profound!

And of course Olbrich provides new references to track down.

Production of light-bodied rum by an extractive distillation process / E. D. Unger, T. R. Coffey
Set Level: Annales de Technologie Agricole. N.º 3-4, vol. 24 (1975), p. 469-495

This is a very complex paper and even if you cannot wrap your head around all the science, you can see massive automation at work. You can also see the birth of spirits made from sugar cane that some like Arroyo would not call rum. For starters, this paper explains how by using computation they can take a beer with a given set of congeners then predict what the output will be given the continuous stills tuning options mainly concerning fusel oil. This explains how a bespoke fermentation for Ron del Barrilito, or even any heavy rum within a producer’s portfolio of other lighter rums, could be spliced into the feed and variables immediately adjusted to give a lower proof ferment with a different level of fusel oil reduction from the usual. This does not give the distiller unlimited potential to pick and choose congeners, but it does give more options to maximize the potential of the still.

Reduction of fusel oil during distillation is shown as a big focus of the paper, but what Arroyo has taught us is that reducing it during distillation jeopardizes reducing rum oil which is the hallmark of rum (yet is seldom discussed). For heavy rums according to Arroyo, fusel oil should be reduced by yeast selection and fermentation optimization. Distillates produced as described in the paper are sort of the antithesis of the Arroyo teachings and are something else masquerading as rum. Yet its all wildly advanced and of course applied to rum first.

Facts about Sugar, 1940, Volumes 35-36, 26-? (part I already got), 35-? (start of part VI), 64-?;id=coo.31924054773571;view=1up;seq=7;start=21;sz=10;page=search;orient=0

Team Pombe and the Yeast Olympiad

Follow @b_apothecary

I think it is finally time to delve into some yeast topics regarding rum. I’ve sort of avoided it though Arroyo states you should always start with yeast selection. Factory design and equipment purchases, Arroyo explains, are dependent on yeast choices. How fast they ferment and their alcohol tolerance dictates how many vats. Do they produce aroma worthy of batch distillation or should you go continuous? It all begins with yeasts.

When I first read the works of Percival Greg in Jamaica and his descriptions of yeast no. 18, I became wildly curious about Schizosaccharomyces Pombe. Pombe is a fission yeast as opposed to a budding yeast so they divide differently. All brewers yeasts are budding yeasts and pretty much no beverage uses Pombe yeast but rum (industrial wineries are exploring Pombe to reduce malic acid because they can metabolize it into alcohol). The name Pombe is Swahili for beer and it was first identified in African millet beers in the late 19th century. It has been explored in conventional beers, but is known to produce off aromas in the context. Not even all rums use Pombe yeasts, but typically those of the grand arôme tradition do (I use that term without nationality because I like the ô). Geneticists have been studying them as a model organism for looking at mutations because of how they divide, so when searching for information you have to wade through a lot of genetic science.

Yeast type seems to be something beverage people have forgotten about and connoisseurs don’t even know to make the distinction. If used properly, Pombe can make the heaviest, most suave of rums, but they can also be used to make straight light rums. Many producers inoculate with them and many other producers accidentally end up with them. Among the serendipitous category, some end up producing a heavy type of rum while most others sort of sabotage their chances of grand arôme by other contingent practices. Typically, producers of heavy rums, are keener on their science and with great care, coax their Pombe yeasts into producing tons of gorgeous aroma.

[Fermentor at Hampden estate in Jamaica, likely a top fermenting Pombe yeast and closely matches the description of Percival Greg’s. Image credit Rum Gallery]

Schizosaccharomyces Pombe yeasts have sub categories just like budding yeasts and there are top fermenting and bottom fermenting varieties. As a rule of thumb top fermenting yeasts produce a fuller bodied aroma and ferment even slower. Pombe yeasts do not produce all the aroma themselves, and the slowness of their ferment means that favorable bacteria can take hold and produce desirable aroma compounds. It also leaves room for undesirable bacteria and Pombe yeasts typically require more care which is why many distilleries avoid them.

Pombe yeasts relate to the dunder process because as a rule of thumb they have significantly more osmotolerance than budding yeasts. This means they can withstand the stress of high acidity, high initial sugar contents, and high contents of dissolved minerals that accumulate in dunder. Jamaica and many other areas likely ended up discovering Pombe yeasts via sloppy fermentation practices where things weren’t measured properly. Empirically it was revealed that dramatically different results could be gotten. There was a time where distillers were just learning about bacteria and how it was inhibited by acidity, so to protect yields they were heavy handed and eventually ended up with a rare yeast type. When acidity is high, Pombe will take hold as the dominant yeast, but bacteria will not and this is a way to get particularly light rums as a result of using Pombe. This idea may have great bearing on older Haitian rums pre-1980’s and many small production Cachaças.

It was initially thought that high acidity correlated to fuller flavored rums but that isn’t exactly true, the Jamaicans were sort of wrong and Arroyo straightened it all out. More on that later, because it gets really profound.

Another point I should make is that fission yeasts relative to budding yeasts have a low frequency of occurrence. That is why they are typically not dominant, but can be made to be dominant as part of a community by messing with fermentation kinetics. The low frequency of occurrence, coupled with being abandoned by the industry, and the rise of in house research by certain sophisticated firms means there are no industrial catalogs of Pombe yeasts to choose from like there is with budding yeasts. There is a Pombe society, but it is a group of geneticists and not a group of rum aficionados.

If you want to mess with fission yeasts, you need to round a bunch up and have them go through a fermentation Olympiad. This is what Jamaican had done very early on and their Agricultural experiment station would send a new yeast out at the beginning of the season. Later in the season they would find that it often wasn’t still dominant. Arroyo conducted his own Olympics with some extra wild results, and the French have held their own games for themselves. Arroyo doesn’t say much on the actual methods of discovery, but he does describe his pentathlon better than anybody.

The big test is the yeast’s ability to produce rum oil, which is the mysterious prized metabolite and something fission yeasts produce more of than budding yeasts. Pombe yeasts have to be found at random (a strategic random), purified, then run through feats of strength. After they pass the rum oil tests, they have to go to the fusel oil event. For grand arôme rums, fusel oil has to be minimized during fermentation because fusel oil and rum oil fractions overlap in the still. If you use a fusel oil separator in a continuous still, or a decanting technique in a batch process, prized rum oil will be lost, so unlike other spirits, rum has to be that much more in tune with its yeasts. You can ferment molasses with yeasts, distill it, and not get rum, (but my God will they try to call it rum!) They will also probably try to adulterate it instead of learning more about fermentation. Rum is that much more profound than other spirits.

I have long wanted to bring fission yeast to New England and I’ve slowly been hatching a plan. My initial plan had to be scrapped as I learned much more. You cannot exactly get a pombe yeast from the catalogs. I mean, you can for $350USD, but it has yet to be vetted and win a gold medal, and it has to compete against a lot of other candidates so ultimately you would need a few thousand dollars just for your first cultures and they’d come with no story. Rum has to have a story, and typically they all do, more so than any other spirit.

I plan on taking a slightly different tack, I am going to do discovery myself, and then hold my own Olympic trials. I will try wide ranging local discovery with various fruits, but it doesn’t look promising (I need to verify that hunch is correct regardless). Isolating budding yeast is easy, but even when understanding their typical kinetics, isolating fission yeast, with their low frequency of occurrence is hard. I have hatched an extra novel plan which would get me a standing ovation with the yeast biologists if I can execute it. I have an extraction protocol with a track record of success and I’ve already been collecting exciting sample media from around the world. Arroyo isolated near all his contestants from sugarcane, but I do not think that is the only way. I’ll have contestants coming from as far away as Sardinia and I have eight potential contestants from within Minnesota alone, that with genetic testing I can give first names to. Will any be the same or will they all be unique? And what will my distribution of tops and bottoms be? Or am I completely wrong and all the gold medal winners must come from sugar cane because they are best adapted? There is only one way to find out! I do have a yeast biologist partner in crime for this so I’m hoping the protocol will be successful.

My initial plan was to understand Pombe kinetics enough to create dominant cultures in varying mediums like apples, raspberries, foraged blueberries, etc very much like what is rumored to happen at Hampden estates. This would also come with free riding bacterial communities. This plan was dashed because though I could possibly construct a starter one way and build a large footing to optimize aroma and fusel oil production. The rest of the wash would be very different and the community would change significantly. An entire community from a starter would bring an elegant sense of terroir, but it would not be correlated to the most extraordinary of sensory values. Until I learn more, my initial best bet is Arroyo style pure culture fermentation.

The majority of the rum industry that found themselves with Pombe yeasts have abandoned the practice and in many cases because it didn’t meet their objectives or technical abilities. For a long time, and for much of the world without any established reputation, rum sold largely on price. Being most competitive required continuous stills which need continuous streams of wash to run. Vats require capital expenditure and to feed the hungry stills, a quick fermenting budding yeast could turn around a vat much faster, thus reducing expense. In many scenarios Pombe yeasts also have less alcohol tolerance than budding yeast which means more energy to separate all the extra water. Arroyo and a few other consultants tell tales of massive distillery wastes due to incomplete fermentations. Pombe yeasts are never singled out as at fault, but these distilleries were never testing the boundaries and limits of their workhorses. Biological control requires chemical control and if you don’t even have that, you just cannot mess with fission yeasts.

We are going to see a fission yeast renaissance. The first step is recognizing their current usage on the market and their usage historically. Did New England rum at Felton & Son’s ever use a fission yeast? They did make very full bodied rums and were using dunder. There is one untapped resource left to possibly find this information (and I’m working on it!). Is Hampden estates using the most noble of grand arôme fission yeast processes? Does Cape Verde end up using a fission yeast? In the previous post I attributed much of their character to cane juice not being defecated or clarified, but if a cachaça producer could end up with a fission yeast, why couldn’t a grogue maker? Answering that question may be as simple as asking how long their fermentation lasts.

The next step is bringing it to the new distillery movement. There are countless new distilleries producing rum but do any of them have progressive yeast labs and is anyone holding systematic trials for their yeasts? (Hint: partner with a university!)

Yeasts we will see are where it all begins, but they guarantee nothing if not followed up with chemical control and more in depth understanding of their specific metabolisms. Next, and after I gather a little more information, we will move down the road and look deeper at comparative fermentation options for rum making.

Follow @b_apothecary

Excise Anecdotes from Arrack Country

Follow @b_apothecary

These anecdotes have been taken from a wonderful 1983 document written by J.P. Rupasinghe presented at a 1981 symposium on palm sap products.

It starts with acknowledgement of a checkered history, there is a tale of fraud, later a gargantuan tragedy, and an ending with revelations of terroir. If this is the first tale from this vantage point I’ve ever found, are others likely to be equally so good?

Some Anecdotes

I would now wish to relate some anecdotes in my 30 years of experience as an excise officer in the checkered history of the excise department. As a young Superintendent of Excise on first appointment, working in Jaffna, living with another officer who now is Head of another department I have something interesting to say. My colleague was used to take a bottle of fresh toddy in the morning instead of his bed-tea as in his opinion it was more invigorating than the tea. Tasting palmyrah toddy especially during week ends was a passtime and was real fun. The best palmyrah toddy that we had encountered in the Jaffna District and its neighbouring Island was found in the villages of Keerimalai and Senthan Kulam in the Kankesanturai area. The sap from the male palmyrah tree in these areas far excelled any other toddy found in the Jaffna district. I feel the strain of the palmyrah trees found therein and the soil and climatic factors matter in bringing about this condition in toddy. When I came soon afterwards from Jaffna in charge of the State Distillery at Seeduwa there was an Asst. Government Analyst on loan to this department for brief period of 2 years at a time. However, the toddy supplies to the State Distilleries at Seeduwa were obtained from contractors who had their topes in the Chilaw area and they were paid on the pure toddy (alcohol) content of 7.5 % on the gallonage supplied depending on the strength of toddy supplied as indicated by the Ebulliometer test conducted by our officers located at the distillery. It was found that large quantities of toddy received had reached the final stage of fermentation and the toddy did not appear genuine. With the collaboration of the Govt. Analyst at the distillery a random test check was done on suspicion for the presence of starch as there was a rumour that boiled rice water was used in preparing this synthetic toddy. One application of this starch test the results were startling and positive. Starch being not a component of toddy the next obvious thing we had to do was to roll the barrels down the drain leading to Dandugan Oya near-by, to find most of the distillery employees were happily waiting at the far end of the drain away from our sight and having their fill. However this action of destroying such toddy had its desired effects and the problem of synthetic toddy was solved. [They probably used iodine to test for starch.]

When I was at Kalutara thereafter in charge of the large storage and bottling warehouses in the Island I happened to be on leave and the young Superintendent attending to my work had been informed that a large vat containing about 3,000 gallons of over proof arrack was leaking. Perhaps it may have been a simple job for a cooper to stop the leak but this young Superintendent had decided to transfer the arrack to another empty vat near by with the aid of a hand pump. Somehow the operation went on till dusk and the warehouse being newly constructed there were no lights. The hand pump had been used to hard work and suddenly the vat went up in flames, a porter who was on top of the vat hit the warehouse ceiling and fell into the burning vat and must have died instantaneously because what we recovered of him for burial was only his pelvic bone. All attempts to bring down fire was in vain and the balance vat containing overproof arrack, 48 in number, had started bursting like Chinese crackers and a good 100 thousand gallons of overproof arrack was lost in the process. This happened in or around 1957. [Friction from the pump built up intense heat and ignited the high proof spirits.]

Special Arrack

Apart from the severe loss suffered by the department at this stage we were faced with the problem of giving the renters arrack for the taverns they had tendered and a solution had to be found to bridge the gap. This was a time the Gal-Oya and Kantalai Distilleries had ample stocks of rectified, spirits which they were prepared to sell. Samples of rectified spirit and coconut arrack were taken by me to the Government Analyst Department in order to find out a suitable blend for issuing to the public as an alternative to coconut arrack. The Government Analyst Department reported that a blend of 2 of coconut arrack to 1 of rectified spirits would be a satisfactory solution. Thereupon the first such blend was prepared by me at Kalutara and the employees (always hard and inveterate drinkers) were asked to taste and express their opinions. They did so with glee, and that was the birth of what is presently known as Special Arrack or ‘Gal’ Arrack. These proportions are not said to be maintained now and what is put out to the market as special arrack is said to contain more rectified spirit than coconut arrack. The consequences or effects that the consumer of this arrack would have in the long run could be a matter for study. Perhaps the recent census showing a negligible increase in the population may be a result of this.

[When we would assume the special style was developed merely to cut costs, it was actually a response to a catastrophic loss due to a great tragedy. Its easy to miss so many of the stories a spirit can tell.]

Quick Maturation

The late Mr. Mervyn de Silva during his stint of service at the State Distillery experimented with the action of wood shavings on arrack in bottles and on his advice I got a miniature vat constructed, and having placed Halmilla wood shavings, roasted slightly, packed in cylindrical stainless steel wiremesh inserted inside the miniature vat we found that Arrack could be made to mature quickly. A usual 5 year maturation in a vat could be reduced to 2 years by this method. However after we went and took up positions elsewhere in the departments it was found that the few gallons of arrack left in the miniature vat was so good in bouquet and taste that it had an excuse for going fast ”evaporated.” Any how this method is still being used on a large scale at the distillery for quick maturation. [“evaporated” means they enjoyed it so much they drank it, but because they record everything for tax purposes, they wrote it off as evaporated.]


In 1968, I went to France on a French Government Scholarship to study the distillery practices in that country, and I had the good fortune to visit many manufactories in that country. What struck me most was the strain of grapes used to distill Brandy in the Cognac district of France. These grapes unlike the more edible and sweeter grapes in the rest of the country were remarkably sour in taste, and year in year out the same grapes, farmed in that district, were used for the distillation of the more prestigeous Cognacs like ‘Hennessy’ or ‘Remmy Martin’, so much so that the saying goes that ‘a Cognac is a Brandy’ but ‘all Brandies are not Cognacs’. The Armanages, the Salyangnecs, the Polynagcs are all Brandies with distinct flavours produced in specified districts. However, in Sri Lanka we have been slaughter tapping the coconut tree in the tapping belt of Kalutara and allied areas for years. To feed the distilleries therein, the State Distillery has had its supply of toddy year in year out from specific areas. The coconut trees found in these tapping areas are presumably of different strains in as much as ‘Kurumba Water’ taste different from different coconut trees, the sap tapped from the spadices thereof must necessarily be different. I say this as a pointer to those who would like to study this aspect intensively because we are still to find the equivalent of the Cognac district and the particular strains of coconut trees to obtain our toddy to produce a better arrack.

[The strange spellings are all the author’s own. I think one might be a corruption of Salignac, the Cognac house. This passage is wildly profound and it makes you wonder how many people visited Cognac and came back similarly inspired in places we would never suspect. And this was 1981, has their market matured enough since to capture terroir? Can arrack make the jump from commodity to fine? I hope so.

Follow @b_apothecary

Dry Rum & Dry Gin? I like mine wet…

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

[This post on spirits acidity was written about five years ago and some how generated a huge amount of google search returns. In the time since, my understanding of the matter has gotten a huge upgrade, but there is still a lot of questions.]

A fairly accessible and historically significant paper on the topic is Studies with Brandy. I. pH by Guymon, Tolbert, and Amerine who were giants in beverage technology.  These papers were planned as a series but due to the “exigencies of war” (WWII) only the paper on pH and another on tannin from barrel aging were published.  Strangely, these two papers do not appear in any bibliographies that I can remember.

I’ll try and pull some unique things out of the paper and I’ll leave everything I’ve written previously in tact below.

“The pH of seven whiskies varied from 3.68 to 4.78, the highest value being a new whisky.” I think the pH of even the new whisky here is lower than some would think due to a significant amount of volatile fatty acids.

 “In rum Valaer (1937) found the pH to vary according to the source, exceeding 5 for Cuban and Puerto Rican rums.  The pH of rums distilled in this country was lower.”  The pre-Castro cuban rums referenced here have a higher pH because they were relatively more neutral and closer to a vodka.  So when we look at these old papers I suspect the pH of new make spirits can say a lot about congener profile.

“The low pH values of young brandies were attributed to the use of distilling material higher in sulphur dioxide.  A portion of the sulfur dioxide passing through the still is dissolved in the distillate and is slowly oxidized from sulphurous acid to sulphuric acid.  Presumably this is not always the cause of low pH in brandies, for 20 authentic French cognacs, in which the sulfate content owing to oxidation of sulfite is relatively low, the pH was found to vary from 3.76 to 4.98, averaging 4.14.”  What they are getting at here is that back in the day a lot of wines intended to be table wines went through the still and because table wines get added sulphur they ended up with a confusingly low pH even though they were probably well rectified and deficient in fatty acids.  When a wine is constructed specifically for distillation sulphites are never added.

“pH’s as low as 2.24 and as high as 7.97 were found in certain anomalous samples reported by Valaer in a private communication giving in detail the original data.” This foot note is historically very interesting.  Peter Valaer was the great IRS chemist who probably saw and deconstructed more spirits of more types than any ever in the history of beverage science.  The foot note shows that the UC Davis guys new Valaer personally beyond just his papers.

“It is therefore evident that the pH of commercial distilled spirits ranges from 4 to 5, that it tends to decrease during ageing, and it appears that rum has a higher average pH than the other distilled spirits.” I think the rums they refer to here are the fairly neutral “dry” rums.

“Some of these abnormally high pH’s are probably due to the distillation of neutralized distilling material and the consequent lack of volatile acids in the distillate.” Neutralizing distilling material with baking soda is practiced by home distillers making spirits from Turbo Yeasts.  Often their fermentations get “pricked” and excess acetic acids needs to be neutralized before distillation but at the risk of converting an ammonium salt into volatile ammonia which can corrode the condensor producing a distillate tinged with blue verdigis.

“The buffer capacity of new alcoholic distillates is so low that the addition of only small quantities of either acid or alkaline substances results in abnormally high or low initial pH; for example the use of alkaline water for cutting may result in high pH. Caramel syrups are not stable in alkaline solutions and the brandies with a high pH precipitated most of their caramel as a gummy, reddish mass.” This reference to buffer capacity might be why UV vodka referenced in the original post is proud of their pH neutrality. Cheap vodka might have a lower pH because un-desired fatty acids remain in their distillates.  When an old fashioned is batched (guilty!), the sugar probably does not precipitate because the pH is far lower than the fairly pH neutral spirit they are referencing which is basically the brandy equivalent of grape drink.

“Newly distilled brandies with a pH below 4 are also abnormal. Valaer (1939) found a number of the young California brandies of very low pH and, as already mentioned, he explained this on the basis of their high sulfurous-sulfuric acid content.” California used to make sloppy shit! but if you look back at the early days of wine as described by Allan Hickenbothan at Roseworthy in Australia, back in the 1920’s they had a 30% failure rate on wines meant to be table wines and they were all sent to the still.  After Hickenbothan discovered the significance of pH and started acidifying wines, what they sent to the still decreased to 5%.



Lately I see the word dry confusingly placed on all sorts of spirits from gin to rum and I don’t really understand what it means. dry is even confusingly used in wine speak. Many people can’t make heads or tales of whether a wine is sweet or not. Is there unfermented sugars or are people referring to levels of acidity? many people think rums are sweet because they are made from sugar but that sugar is transformed into alcohol as well as not-volatile so if rum has sugar it is added post distillation. Well whats the deal?

If like wine, dryness often ends up referring to acidity, what is the acidity of spirits? Should un-aged spirits mostly be the same and there be some difference in aged spirits? is there perceived sweetness due to high extracts in spirits like some times is encountered in wine?

The UV vodka website proudly claims their product is close to pH neutral relative to other budget producers who acidify their product for some spirits tax loophole. This makes really no sense to me but the budget producers would definitely have some dry booze. Could these practices in neutral spirits be born out of some sort of tradition? Should my C.J. Wray dry rum be fairly low in pH? and if it is, would the result be due to additives or stuff naturally going through the still?

Maybe to solve some of the mystery I should calibrate my Hanna Instruments pH pen and have a go at the spirits that are laying around.

Calibrated with fresh solution.

Whole foods distilled water. pH??? Well my distilled water was below 7 which is kind of a bad omen, but maybe acid is attached to my electrode from my cleaning solutions etc? Maybe the temperature is messing with things? Well I put on a new electrode, calibrated it and I still can’t get a 7 out of this distilled water but maybe its is messed up.

C.J. Wray dry rum pH 4.85

Gordon’s dry gin pH 6.90 <— switching back and forth and this rockets back to 6.90 so the pen works?

Myer’s platinum white pH 4.42

Clement VSOP pH 3.78

Back to the calibrators… things check out… more or less… I tried to go back and forth between samples to duplicate my initial numbers. More or less they check out.

Batavia Arrack Van Oosten pH 5.02

Seagram’s Distiller’s Reserve pH 5.13

Trimbach Framboise raspberry brandy pH 6.80

lemon juice pH 2.37 (time for a cocktail!)

So wow, I don’t really have too much confidence in the tester but I think it can still teach something about what we drink. It is strange how drastically different Gordon’s and the Trimbach are from the others. Your choice here would apparently have a large impact on balancing a sour. Are the results here the reason the rum & coke is more popular than the fairly acid neutral UV with coke? Harold Mcgee puts black coffee at pH 5.0 and yogurt at pH 4.5. So are the results here negligible because we pile on the sugar with our mixers or are these pH factors important in shaping consumer preference over the long run?

Now I’m curious how the more mainstream gins that I work with at the bar stack up, and how does all this acidity get there in the first place? any insights?

I haven’t really put things to test on what comes through my still, but now I’m even more curious and I think I’m going to have to test some things… distilled, citric, malic, tartaric, and acetic acids… and it was the last of my bottle, but if I added baking soda to the low pH Clement would it have fizzed? could I neutralize that acidity?

Do some dry gins have more acidity now because the palate needs it in a martini (or maybe not, it is my assumption from loving dry wine) but no one wants to get it from dry vermouth. So does a great marriage of gin and dry vermouth like you see in weird reviews really have to do with finding a most harmonic pH?

Quite a lot of new mixology questions.

Follow @b_apothecary