Yeast in Rum (or S. Pombe Revisited)

Following on from the three part collected article titled “Aeneas Coffey, John Dore and Foursquare”, Richard Seale posted an in depth look at “Yeast in Rum” in a 6 part series on his personal page, with his agreement I have again collated them into one single reference article below.

Yeast in Rum (or S. Pombe Revisited)

Part One – Yeast History

Back in October/November 2019, I created a quite a stir with some comments and a very brief post challenging some of the myths being created around the novel sacred cow that is S. Pombe yeast. At Foursquare we carry out natural fermentations (which contain S. Pombe) and having made some ‘high ester’ rums last year, it seems a good moment to make a further comment giving more details on the work of Jamaican chemists Percival H Greg, Charles Allan and S. F. Ashby.

A Little History:

Yeast cells were among the first microbes seen in early microscopes and some of the earliest observations concluded it was produced by fermentation rather than the agent of fermentation. In 1755, Dr. Johnson is his famous dictionary defined ‘yest’ as ‘the foam spume, or flower of beer in fermentation’. See also his cross reference with the definition of ‘barm’.

Lavoisier (1789) investigated wine fermentation by qualitative methods and could not find a role for yeast in the reaction that produced alcohol. However, by this time scientists believed yeast (or ferment as it was called) played a role in starting the process. Berzelius called this catalysis. German Scientist Theodor Schwann identified yeast as a living organism and call it ‘zukerpilz’ – the sugar fungus (or sugar mushroom). His colleague Franz Meyen that provided the modern latin name in 1838 – saccharomyces cerevisiae – literally ‘beer sugar-fungus’ for the species of yeast in common use today (through the use of thousands of strains of the species). Pasteur also supported the idea that fermentation was a biological process, that is a process by living organisms.

Famed German biologist Justus Von Liebig disagreed with this ‘vitalist’ theory arguing that alcoholic fermentation was a purely chemical process – no living organisms were involved – and this led of one of the most famous disputes in Science. Liebig believed the yeast was kind of nitrogenous organic compound which decomposed the sugar and a product was deposited described as an insoluble ferment. This ferment could be used as ‘ferment’ in another sugar solution. Pasteur would eventually settle the debate through a set of brilliant experiments.

Ultimately neither scientist was entirely correct or entirely wrong. Eduard Buchner obtained pure samples of the fluid inside the yeast cell and discovered that the fluid could ferment a sugar solution despite the fact the yeast cell was obviously dead. He realised that fermentation reactions were a chemical process inside the yeast cell by what we know today as collection of enzymes. So alcoholic fermentation is after all a bio-chemical process. Buchner would publish his work in 1897 for which he would be awarded the Nobel Prize.

Pasteur’s work would extend to improving wine making. He observed that soured wine was caused by the presence of lactic acid. He further observed that sour wine contained not only oval yeast cells but small rod shaped bacteria. While alcoholic fermentation occurred via yeast, lactic acid fermentation occurred via bacteria. Pasteur developed the process of heating the wine to a specific temperature for a short time to kill the bacteria a process we know today as ‘pasteurisation’ which would eventually find widespread use in the beer, milk and juice industries.

Danish mycologist Emile Christian Hansen, working at the Carlsberg Laboratory would take yeast understanding a step further. Pasteur had not fully solved the problem of brewing cloudy and off tasting beer despite pitching bacteria free yeast cultures. Pasteur had seen yeast as homogeneous cells, Hansen was the first to isolate different strains/species of saccharomyces yeasts. He discovered that certain strains were directly responsible for the cloudy beer and so by isolating and selecting particular strains for the brewery the problem of cloudy and sour beer could be solved. So now it was necessary to not only eliminate bacteria from beer fermentation but also so called ‘wild yeasts’.

The work of Liebig, Pasteur and Hansen are important to understanding the work of two giants of the Jamaica Rum industry – the planter and distiller Leonard Wray and the chemist Percival H Greg which we will consider in Part two.

 

Part Two – Wray and Greg

Leonard Wray (family to the more familiar J Wray) published his famous treatise in 1848 and his understanding of fermentation was based on the work of Liebig.

For Wray, the nitrogenous matter that would initiate fermentation was already contained in the raw material and so no yeast (or ferment) needed to be added:

“it is seen that molasses and skimmings each contain sugar, gluten, and water; so that fermentation will occur spontaneously in them without the intervention of any foreign substance, such as yeast”

As Lavoisier had quantitatively demonstrated before him, Wray stated the elements of the yeast (the glutenous or albuminous matter) “take no appreciable part in the transposition of the elements of the sugar ; for in the products resulting from the action, we find no component part of this substance”

For Wray, as Lavoisier, the yeast had no part of the final product, for Wray “the peculiar flavour of rum is generally understood to proceed from the resinous, aromatic gum (or essential oil), contained in the rind of the cane”.

Wray relayed an anecdote which marvelously echoes today:

“It is not more than a few days ago, that I was asked by a person why yeast was not used by our sugar planters as ferment instead of dunder ; intimating in very significant terms, that he considered all the West India distillers a very choice pack of fools. Now, this person says that he has been for a long while manager of one of the largest distilleries in the world. He has written a pamphlet on distillation, with a view to enlighten the minds of all distillers, and no doubt fancies himself possessed of all possible knowledge of the subject. And yet this person, who is a clever man, and no doubt very competent to instruct English distillers, does not know what dunder is, or what is its use in the fermentation of wash.”

Wray in his seminal work put his erudite view in the strongest terms, “no foreign agent — such as yeast — is necessary. Nay, further, that such is extremely undesirable ; as it would change altogether the character of the fermentation” (my emphasis).

Wray’s understanding of fermentation was not precisely correct but in practical terms, he was not wrong. Moreover, he was prescient. Everything needed for fermentation was indeed there, no ‘foreign agent’ was needed but the rise of pitched yeast with isolated, sterile yeast strains would forever change the fundamental character of rum fermentation not just in Jamaica but in every rum producing country. Today, just a handful of rum distilleries operate under Wray’s philosophy, almost all of them in Jamaica, most notably the Hampden and Long Pond Estates in Trelawny.

The first serious challenge to this approach would come from Percival H. Greg. Greg was the first chemist to isolate individual strains of yeast as found in Jamaica distilleries. Greg was strongly influenced by the work of Emile Hansen and travelled to Copenhagen to work at the Carlsberg laboratory under the supervision of Hansen’s colleague, Prof. Alfred Jorgensen. At the Carlsberg Lab, he conducted a series of experiments on molasses and dunder sent over from Jamaica. Greg became convinced of the merits of isolating, selecting and pitching a strain of yeast as was now becoming practice in breweries and distilleries around the world. Writing in ‘The Sugar Cane’ in 1893, Greg advocated:

“Not only must we do away with spontaneous fermentation by using a ‘pitching’ yeast, as brewers term it, i.e. adding some previously prepared yeast to set our vats in fermentation at once, but I strongly recommend the selection and cultivation of a suitable type of yeast in a state of absolute purity”

Greg was not alone in his ideas. Pairault (1903) and Kayser (1913) also suggested that starter culture yeasts for rum production should be selected. Both Pairault (1903) and Kayser (1913) recognized that bacteria were also endemic to rum but in their view they negatively impacted on production efficiency and quality. Fahrasmane (2002) reported that “after 1918, some distillers in the French West Indies who wanted to increase the alcoholic yield decided to put into practice the advice of Pairault and Kayser on pure fermentations. Although the result was an increase in yields, the quality of these products evidently fell because of their increased chemical neutrality”.

The star of the show of the strains tested by Greg in Copenhagen was a fission yeast, aka Schizzosaccharomyces Pombe (S. Pombe) which he dubbed No. 18. It is this earliest work in yeast selection that still resonates today in those who believe this type of yeast to be the holy grail in the search for the best Jamaica rum. Following Pasteur and Hansen, Greg at this time saw bacteria as only a source of potential disaster.

Enter Charles Allan who took entirely the opposite view. We will examine that in Part three.

 

Part Three – Allan and Ashby

In 1903, the Jamaica Board of Agriculture decided to hire a specialist Fermentation chemist as well as to set up a sugar laboratory, a fermentation laboratory and an experimental distillery with a 50 gallon still with a “telescopic head” and detachable retorts. The purpose was to study rum making with a view to improving yields, quality and studying the types of yeast involved. Charles Allan would be given a three year contract for the role under the supervision of legendary ‘Island Chemist’, H H Cousins. In 1905, it was Allan who supervised the implementation of Cousins High Ether Process at a specially built plant at Hampden Estate. A process still in use today.

Allan was able to show that the “flavour” of Jamaican rum was not the result of alcoholic fermentation by yeasts but due to acidic fermentations by bacteria.

“The point I wish to emphasize at present is that the value of rum depends mainly on the secondary products [the congeners] it contains. I will show you by means of experiments in the laboratory that cane juice or molasses fermented by yeasts alone produce but very little of the secondary products. These, therefore, must be formed by other organisms, chiefly bacteria which swarm in the washes of Jamaican distilleries”

Allan contrasted the modern approach of breweries of his era with the approach needed by the Jamaican distiller to make the best rum.

“In the most up-to-date breweries now not only are all bacteria excluded but yeast which has been carefully cultivated from selected seed are only used. The effect of this on the article produced was to alter to an appreciable extent its flavour but it ensured its stability in character and in a short time the newly acquired flavour got to be appreciated. In the case of Jamaica rum however we have an article of a very different nature to deal with. The flavour is of a very pronounced character and is one of its chief assets. The flavour of beer is very delicate and is produced by the yeast itself whereas I am of title opinion that the yeasts contribute but a small amount of the flavour of rum”

Allan’s successor at the Jamaica Government Laboratory was S. F. Ashby. Ashby had also studied yeasts at Copenhagen and was the Bacteriologist at famous Rothamsted Experimental Station in the UK before arriving in Jamaica in November of 1905.

He set about to explore further the contribution of yeast to Jamaica rum. He set up ten experiments with sterile washes seeded with strains of the fabled S. Pombe, selected due to the earlier work of Greg. The results were a disaster.

“The rum could hardly be called by that name, and it showed the same character for all ten yeasts; in no case was any characteristic flavour produced”.

Ashby continued with another series of experiments where acid was added to the otherwise sterile washes seeded again with S. Pombe.

“The conclusion to be drawn from these experiments is that, whereas none of the fission yeast isolated from the estate washes was able to produce flavour on its own account, the top yeast owing to its slower fermentation admitted a greater amount of chemical ether production in a wash originally high in volatile acids. The latter result is in accordance with distillers’ experience as they consider that a wash showing a strong fatty head due to the top fermenting fission yeast yields the best flavoured rum.”

Ashby set up further experiments again with added acids but this time observing the behaviour of each species of yeast (S. Cerevisiae and S. Pombe) with each type of acid (acetic, lactic, butyric) these being the common acids in distillery washes (produced primarily by bacteria).

“The ability of the budding type [S. Cervisiae] to multiply and ferment more rapidly from the outset in the weaker acid liquors, like cane juice washes and fresh skimmings, explains why this is the only kind found in such liquor the acidity of which is generally under 0.5%. In the usual estate washes containing dunder, molasses, acid skimmings, and frequently specially added acid, [this would be known as ‘flavour’ made in a muck pit or trash cistern ] the budding yeast [S. Cerevisiae] is largely suppressed, but the more slowly developing and very acid resistant fission type [S. Pombe] takes possession, and is practically the only form found in washes the acidity of which is 1.0% and over”.

Ashby demonstrated in experimental work that the remarkable qualities of S. Pombe are not in its ability to produce flavour of its own account but its ability to make alcohol in washes that are set up to make the characteristic flavour of high ester Jamaica Rum. Its slow rate of fermentation is also particularly important in allowing these characteristic flavours to be developed rather than rapidly consuming the available nutrients and producing the sterilising alcohol which would retard their development.

After his contact was concluded, Ashby would continue to have an illustrious career, he would also work in Trinidad before culminating his career as the mycologist at the Imperial Mycology Institute located at the Royal Botanic Gardens in Kew.

In fact Greg too in his work had also demonstrated that S. Pombe was no panacea – a simple trial of No. 18 in the absence of dunder produced no flavour. In his final paper on Rum aroma published in 1895, Greg concluded:

“If one may be allowed to theorize a little, there seems sufficient grounds for concluding, from the results which I have up to now attained, that though the aroma of rum is in the first instance derived from the soil, that this influence is chiefly potential not actual; that it is latent , dormant , and only brought into existence during the process of manufacture”.

Greg was back to Wray even before the arrival of Allan and Ashby.

So what does yeast contribute? We look at that in Part four.

 

Part Four – Yeast Flavour

Yeast is a bit of sacred cow itself in distilling, not least of all the current fad of S. Pombe. The primary mission in this series of posts is to explain the role of yeast in the context of traditional Jamaica high ester rum, not to diminish its broader importance. The role of yeast in any spirit category is wholly dependent on the culture in which that spirit is made. Yeasts and bacteria are the organisms directly responsible to creating flavour in alcoholic fermentations. Allan summarised well the challenge of striking the balance between the two:

“In making rum the first consideration is to produce alcohol. This can be done by encouraging the development of yeasts but in so doing you are discouraging the growth of bacteria and again if you encourage the development of bacteria you are setting up conditions which are against the interests of the yeasts. You must choose a middle course and it is just here where our greatest difficulty arises.”

Fortunately yeast does not only make alcohol but flavour congeners are produced as by products of yeast metabolism. These include higher alcohols (propanol, amyl alcohol etc), acids (acetic, lactic etc) esters (ethyl acetate), acetaldehyde and diacetyl. Further esters are formed by combining the produced acids with alcohol. Nykanan and Suomalainen (1983) listed 400 flavour metabolites of yeast fermentation. Of course only the volatile ones that pass over into the distilled spirit would be relevant for rum or whisky.

Yeasts are not a typical fungus in that their spores do not migrate by air currents. They are thought to be carried in the stomachs of insects. Recent research in Belgium – Christiaens et al 2014 – showed that fruit flies could use the aromatic odour produced by yeast to find fruit. The yeast helps the fruit fly find the fruit and the fruit fly helps the yeast move around. In short, fruit flies defecate yeast, and yeasts defecate alcohol (and some nice smelling bits).

Yeast autolysis is the degradation (by its own enzymes) of the cell wall and its contents following the death of the yeast cell. Yeast death is not a function of age but of how many times the cell has reproduced. This autolysate or ‘yeast extract’ notwithstanding its foremost importance to making marmite plays an important role in flavour development in fermented wines and spirits. Autolysis is strongly influenced by acidity and ethanol both of which are abundant at the end of fermentation. Several flavour compounds are released during autolysis including fatty acids (which will make esters and aldehydes) and heavy esters (e.g iso amyl caproate), terpenes (thought to be the constituent of what famed Puerto Rican chemist Arroyo called ‘rum oil’) and higher alcohols such as iso amyl alcohol.

Yeast autolysis is a very important part of the champagne method where the where the wine is kept in contact with the yeast autolysate in the bottle. It is also known as the ‘sur-lie’ method for making white burgundy. The autolysate is also a source of nutrients for bacteria. Greg, in one of his caveats for using yeast No. 18 advised it was important that the ‘dead wash’ sit for a couple of days before distillation. Ashby noted that S. Pombe produced far more autolysate than S. Cerevisiae. This is because of the double wall thickness of the fission yeast. This extra biomass is mainly polysaccharides. It does not contribute to flavour in distilled spirits save for providing nutrients to bacteria.

So just how did Jamaicans strike the balance described by Allan. That is for part five.

(pictured – A schematic overview of the main metabolic routes inside the yeast cell contributing to the synthesis of higher alcohols and esters when inserted in the fermenting medium)

 

Part Five – Striking the Balance

The addition of dunder (and its analogs of sour mash in bourbon or backset in whisky) as practised by all rum makers in the West Indies from the 17th century was precisely to set the balance described by Allan. By adding the acidic dunder at the outset, the acidity of the wash was increased to bring it into a zone that was still tolerable for yeast but inhibitory to bacteria. Favouring yeast was paramount because making alcohol is paramount. No point having bacteria produced flavour if they have gobbled up all the sugar and there is little or no alcohol. Many distillers today still adjust acidity in their pitched yeast fermentations by the addition of sulphuric or other acids.

Jamaica (and to a limited extent Barbados) would dimensionalize the molasses/juice/water formula of Wray by the addition of soured juice skimmings and something literally called ‘flavour’. Flavour was produced by a sort of parallel bacterial ferment using cane materials in a ‘trash cistern’ or ‘muck pit’. Each high ester rum making estate developed their own formula and method for ‘flavour’.

It is this use of soured juice and ‘flavour’ that tips the pendulum of aroma development in Jamaica Rum to bacteria over yeast, not that we wish to understate the importance of their symbiotic relationship. The creation and addition of ‘flavour’ in the Jamaican high ester rum making is the cultural equivalent of a bourbon distiller selecting and pitching their own favoured yeast strain. For wine and beer, yeast is king. In Scotch whisky, they do not boil the wort as in beer but rather heat it to 64C for a short time and so some bacteria is inevitably present during fermentation. With the early dominance of pitched yeast, the bacteria, chiefly lactic acid producing bacteria makes its presence felt at the end of fermentation – no role required for S. Pombe. Yeast autolysis would provide the nutrient requirements for the lactic bacteria. Late lactic bacteria is now widely considered to have a positive contribution to the flavour of the whisky (Geddes and Rifkin 1989). So in Scotch whisky, yeast is still king but the pendulum is swung a little in the direction of bacteria.

Today nearly every beer, wine or spirit including much of the rum in Jamaica is now made by pitching selected yeast strains, the practice outlined by Hansen in the late 19th century. The yeasts used are mostly of the saccharomyces type particularly the species saccharomyces cerevisiae for which there are literally thousands of strains. Saccharomyces types have such broad application because it fits the needs of the distiller so well. It is very efficient producing rapid fermentations, dominant (killer strains release a toxin to kill wild yeasts), tolerant of high alcohol content and by species/strain selection it reliably produces the desired flavour.

The yeasts used in whisky industry are mostly S. cerevisiae although various secondary species have been used. Lager yeast is S. pastorianus, ale yeasts include S. cerevisiae and apparently some S.bayanus strains. The wine industry mostly use S. cerevisiae and/or S. bayanus. Some wine makers and craft brewers use non saccharomyces types including Kloeckera, Saccharomycodes, Schizosaccharomyces, Hansenula, Candida, Pichia and Torulopsis. The use of non saccharomyces types is more practical in brewing because they can use a sterile wort. Trying to use non Saccharomyces types in rum is impractical as wild Saccharomyces strains will quickly dominate. Peynaud & Sudrand (1986), Haraldson and Rosen (1984) and Fahrasmane et al (1986) all found that Schizisaccaromyces strains in pure culture produced very few congeners.

In the past, Schizosaccharomyces yeasts were often detected in wines suffering from organoleptic faults through the appearance of sulfidric acid (hydrogen sulphide), acetic acid, acetaldehyde, acetoin and ethyl acetate. Most of these would not necessarily be a fault in rum making. Further research with highly selected strains of S. Pombe showed much better results (for wine) but their attraction for wine making was more related to the ability of this yeast to degrade malic acid rather than any remarkable aromatic profile. It should be noted that Ashby reported the existence of a ‘fruit ether’ yeast of the budding type, that is to say it was not S. Pombe.

It has been suggested in some circles that S. Pombe needs to be “reintroduced” into rum making. It is a ridiculous statement, it never left. S. Pombe plays its usual role at Hampden estate as it has done for over 250 years and S. Pombe can be found wherever rum is made. Several early studies identified S. Pombe in molasses and juice in rum distilleries in the Caribbean. More recently Fahrasmane (1988) found S. Pombe prevalent in Haitain distilleries. Bonilla-Salinas et al (1995) found S. Pombe in Mexican distilleries and Green (2015) found significant counts of S. Pombe yeasts in molasses at Bundaberg in Australia. You can find S. Pombe in our fermentations at Foursquare where their role varies depending on the rum to be produced.

The revised interest and circulation of the papers of Greg, Allan, Ashby et al by bloggers, enthusiasts, distillers and writers is absolutely to be applauded. I cant praise these efforts enough. That this 100 year old work still serves as inspiration to younger craft distillers is a joy to observe. My caution is not to take the work in isolation and consider it hand in hand with later work and the practical operations of West Indian Rum today that has built on and added to that knowledge. That such is not readily available via google should not detract from its value. As Wray warned, do not take the West Indian distillers for a ‘pack of fools’.

We do not need to reintroduce S. Pombe to rum, what we need to do is protect the traditional way in which it is used.

We will consider that in part six.

 

Part Six – The Jamaica GI

The core of traditional Jamaica rum making is the art of using simply sugar cane derivatives, spontaneous fermentation and batch distillation. Distillers were able to improve and innovate without ever breaking these fundamental core principles. In 1893, the year Greg published his first paper, 148 Jamaica distilleries operated this way. By 1948 there were just 25. Today just one distillery owner exclusively practices these methods. Pitched yeast and continuous distillation have changed Jamaica Rum (and Barbados Rum) forever as warned by Wray and J C Nolan (special commissioner to the UK for Jamaica rum) respectively. These two horses have bolted. There is no putting them back. But we can stop here and forever protect these methods.

In 2016, the Jamaican distilleries by unanimous agreement restricted the addition of fermentation agents ( those foreign agents of Wray! ) to yeast and only to yeast of the saccharomyces types. There was no restriction on native yeasts and bacteria proceeding in their normal spontaneous and natural way. How could they? Forced Sterilisation? One-third of the shares in a single Jamaica distillery changed hands in 2017 and since then, that pernicious shareholder has sought to discredit the GI as registered – most wickedly by mischaracterising the GI restriction as “narrowing to one genus of yeast we are wiping out hundreds of years of history of rum making”. Willful ignorance or just ignorance, I let my hopefully now better informed readers be the judge.

The distillery has now demanded through their team of lawyers that the Jamaica IP office unilaterally rewrite the GI to their personal specifications despite the protests of the remaining three distillers. One of my Jamaican colleagues, very high in the industry there, called this “insidious re-colonialization, putting his own selfish needs ahead of the industry and in contravention of the spirit of the GI.” I call someone who acquires a minority interest in a Jamaica distillery in 2017 and who then demands the GI be rewritten to their unilateral specification a megalomaniac.

Among the demanded changes, all designed to render the GI nugatory, is a demand to add other fermenting agents including bacteria. So pitched yeast and now pitched bacteria. A kind of rapid, cheaper ersatz Jamaica rum to be made and sold under a cloud of trite, hyperbolic marketing clichés. Pitched yeast and pitched bacteria take us further away from the true terroir of Jamaica Rum.

I suspect part of the motivation to rewrite the GI is the delusion based on the once again trendy advocation of Greg that magical Jamaica Rum will produced by simply pitching S. Pombe. It takes a high level of Dunning-Kruger type stupidity to think you are going to “innovate” Jamaica Rum by simply changing the brand of added yeast. You need to take West Indian distillers for a ‘pack of fools’ to believe this.

I will let Maggie Campbell, artisan distiller, yeast guru and esteemed colleague have the last word:

“It is wise to remember this is the life’s work and lived experience of these GI supporting Jamaican producers, they are not unwise or foolish, rather they are guardians of their culture and community. No one needs to benevolently jump in and fight to save Jamaican rum from itself, they are protecting it just fine themselves and the GI laws are set up to do just that”.
“If you do not want to participate in the community standards and cultural practices then you do not also get to demand instant access to leverage that community’s and culture’s hard won reputation for excellence.”

 

Again, huge thanks to Richard for allowing me to collate and reproduce the information here

© Steven James, Rum Diaries Blog and Richard Seale. Unauthorized use and/or duplication of this material, both written and photographic without the express and written permission from this blog/sites author and owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Steven James, Richard Seale and Rum Diaries Blog with appropriate and specific direction to the original content.

Aeneas Coffey, John Dore and Foursquare

Richard Seale recently posted a very informative and interesting series of articles surrounding Continuous and Batch Distillation on his personal page, with his agreement I have collated them into one single reference article below.

Aeneas Coffey, John Dore and Foursquare

Part One – The Continuous Still

Aeneas Coffey was not the first to invent the continuous still, nor was it the first continuous still to be used in Scotch Whisky however between 1834 and the 1876, seventeen newly installed Coffey stills would be making whisky in Scotland. It proved the foundation for the development of blended scotch whisky (developed around 1860), arguably the most successful spirit category of them all. How did it all happen? What follows is really only a brief overview of a history that is both very complex and very profound.

The late 18th century through the mid 19th century saw remarkable developments in spirit distillation. A drive to increase proof, efficiency and throughput underpinned these developments. We are focusing on the British, Irish and European developments as this directly impacted the West Indies but the American story is also very complex and worth your time.

Early stills by Adam (1801), Pistorius (1817) and Corty (1818) and several others too numerous to detail were essentially modifications of the simple batch (pot) still to add fractionation to simple distillation. In London at the Belmont Distillery in Vauxhall Jean-Jaques Saint Marc patented a batch (pot) still with a rectifying head in 1824. While used by Saint Marc for potato spirit, this concept would be a forerunner of the carter-head and the ‘Lomond’ still at Loch Lomond distillery. A notable step (see the post script) but still in the realm of discontinuous (ie batch) distillation.

The first genuine continuous still was patented by Jean-Baptiste Cellier-Blumenthal in 1813. In 1828 Robert Stein, a member of the Stein-Haig distilling family would also patent a continuous still and this would be the first licensed continuous still used in Scotland at Cameronbridge in 1830. Coffey would first patent his continuous still in 1830 and it bore remarkable similarity to the Cellier-Blumenthal still.

Aeneas Coffey had been an Irish Inspector of Excise until his retirement in 1824. During his work as an excise officer he invented the Spirit Safe an early insight to his genius. Purportedly of French birth he may have had contact with the work of Cellier-Blumenthal. It was also thought he was familiar with another early continuous still of Cork distiller Anthony Perrier patented in 1822 as well as the continuous still of Robert Stein. Coffey’s Father, Andrew Coffey was the engineer in charge of the waterworks for the Dublin Corporation and reputed to be quite ingenious. He may have also had an influence on Coffey’s engineering skills. Coffey’s first still was at Dock Distillery in Dublin and licensed in 1832. This distillery was not successful and the business was soon changed to one of still manufacture. The first Coffey still in Scotland was at Grange in 1834.

Coffey proved not to be successful in Ireland. Kerr (1946) humorously reflected:

“between good advertising and the effeminate palates of the English, which were not robust enough to appreciate really good whisky like the Irish, this type of whisky [blended] captured the English market and still holds it to an undeserved extent”.

The reasons were likely more nuanced. The early Coffey stills used iron pipes which gave the whisky an unpleasant flavour no doubt contributing to the early failure. Ireland did not license small distillers and legal Irish whisky was dominated by large stills. We suspect this would have played a role in making Coffey’s continuous still less attractive by comparison. Big pot stills would have good throughput if not the fuel efficiency of the continuous still. Ironically, it was Coffey in his role as Excise Office who suppressed the small illicit distillers. In 1810, he was left for dead having been attacked with a bayonet during the ‘poitin wars’. A reward for the capture of his attackers was unsuccessful, excise officers then as now were less than popular.

In 1835, the firm Aeneas Coffey and Sons was established in Bromley in the UK. His failure in Ireland contrasted by early success in Scotland (Inverkeithing and Bonnington had soon followed Grange) and potential sales of his still to rectifiers and gin distillers probably prompted the move. In 1840, Aeneas Coffey Jr established the first patent distillery in London at Lewisham which ended in rather unfortunate circumstances. The Secretary arranged for a large release of spirits from bond and presented the cheque for excise duty at a Directors meeting which did not contain the payee’s name. The secretary filled in his own name, cashed the cheque and was never seen again. The distillery went bankrupt and the Coffeys once again continued on as still makers.

The success of the Coffey still was really due to the evolution of the original design which had been little more than an improved Cellier-Blumenthal still. By 1840, the Coffey still would have copper piping, copper plates (trays) perforated with bubble caps and the still was split into two columns – analyzer (or stripping) column and the rectifying column. This separation of stripping and rectifying would be the foundation of nearly every spirit still in operation today. The use of perforated copper plates (trays) would be a marked improvement on the Stein continuous still which did not have contacting plates and the wash needed to be misted to ensure good liquid / vapour mixing. Even the Haig family would install a Coffey still.

The Cellier-Blumenthal still would also be improved by French Engineer and Dutch Sugar Trader Armand Savalle and by French Pharmacist Louis-Charles Derosne. Savalle and Cellier-Blumenthal were collaborators. Cellier-Blumenthal would sell his patent to Derosne who improved it and filed his own patent while Savalle continued to work independently. Savalle stills can be found today in Demerara and the French Islands of Martinique and Guadeloupe.

While some un-malted grains had been used by highland single malt distillers the advent of the continuous still precipitated the split where highland batch stills were solely single malt with the cheaper un-malted grains going to the lowland continuous Coffey stills. This more economic and more available ‘grain whisky’ in the hands of entrepreneurs like John Dewar, James Chivas and William Teacher was the foundation of the enormous success that Scotch Whisky is today. Some luck played a role as well. In 1863, there was the phylloxera in France which had affected most of Europe by 1879. Blended Scotch filled the void for the well to do English created by shortages of claret and brandy.

The influence of raw materiel on the acceptance and adoption of the continuous still should not be underestimated. We see the same in rum. Demerara was the first to develop vacuum pan sugar – the famed Demerara sugar – but the corollary of that is vacuum pan molasses lower in value to muscovado molasses and Demerara was the first of the anglophone producers to adopt the continuous still. In Martinique, early restructuring of the sugar industry into central factories (and thereby pan sugar) in the mid 19th century is the pre-cursor to the city based (Saint Pierre) production of Rhum Industrial with pan molasses.
In Barbados the rum industry collapses after 1870, due to taxation and economic malaise. By the 1890s, the only estates still making rum are using lower value pan molasses as the famous ‘Barbados Molasses’ (made either as the prime product of the estate or secondary to muscovado sugar) is too valuable to be converted into Barbados rum (which is only sold locally at this time). Barbados would see its first continuous still using pan molasses in 1893 to fill the void as muscovado estates went out of rum production. By the 1920s centralisation of sugar factories (producing pan molasses) would be well underway and two more continuous stills would follow – one at Mount Gay and another in Bridgetown.

For Jamaica by contrast, rum was the primary product for many estates as it was more valuable than Jamaica Sugar. Rum in Jamaica was made from cane juice (Appleton) or ‘first boil’ molasses. Jamaica would not adopt the continuous still until the 1960s.

Notwithstanding the success of still sales to Scotland, the business of still making slowed by the late 1860s and in 1872, Philip Coffey, son of Aeneas would transfer the business to his long time foreman John Dore. Aeneas’s grandson, Aeneas H Coffey would act as consultant to John Dore for many years. By 1887, business would revive and Barnard’s – ‘The Whisky Distilleries of the United Kingdom’ – published that year reported Coffey Stills in all major Scotch Whisky distilleries.

John Dore & Co Ltd would continue as successors to Aeneas Coffey, still operating from Bromley and supply Coffey Stills to the West Indies including to Jamaica, Barbados, Guyana, St Vincent, St Lucia and Grenada. Coffey stills and their derivative designs would be also be sold by Scottish still makers such as Blairs and McMillans including to rum distillers in the West Indies. Following the general demise of British manufacturing, Blairs would cease operation in 1977 and John Dore would cease operating in the early 1990s although the trade mark was sold and has been used subsequently on stills built by other copper works. McMillans continues operations till this day although now it exclusively builds pot stills.

Post Script:
The addition of rectification in 1824 to a batch (pot) still before the development of the continuous (column) is notable. In fact as early as 1813, Florentine Baglioni added a column section to a batch still for grappa. Unfortunately, it did not work well with the ‘vinnacia’.

Today terms such as ‘hybrid still’ are a source of confusion. There is no such thing as a hybrid still. The dichotomy is not pot still v column still but batch still v continuous still. All still designs fall into one of the latter two categories. The addition of fractionation or enhanced rectification to a batch still is still a batch still. The simple batch still relies solely on the lyne arm for rectification. Enhancing this effect does not change the fundamental nature of the still.

A batch still will produce a changing output over time (colloquially the heads, then hearts, then tails) from a single charge (batch) that itself changes as it is distilled. A continuous still produces an unchanged output that varies by position (not by time) on an unchanging charge that is fed continuously. Heads, hearts, tails are drawn off simultaneously from different positions. This is the fundamental distinction between the two processes which also explains why the two can never make the identical spirit.

Early column shaped stills (e.g. the columnar Pistorius still) should not be confused with a column or continuous still, it was a batch still and the Savalle or Cellier Blumental stills are not fitted with “a pot still” just because they had a pot shaped base/kettle – there were in fact continuous (or column) stills.

Part Two – The Batch Still

The myriad of still patents developed between the late 18th and mid 19th century is extraordinary and the few mentioned in part one does not do it remotely justice. This work, applied to simple batch distillation led to the development of the continuous still and the distillation world never looked back.

Curiously, the extensive developments on batch distillation had little impact on the batch (pot) stills of Scotland, Ireland and Cognac and they continue to employ simple batch distillation, either double or triple to make whisky and cognac today. To see advanced batch distillation in the 19th and 20th century, one must travel to the West Indies and observe rum distillation.

It is often claimed that the double retort still used in West Indies is an “Adam’s still”. No explanation is ever offered as to why the English colonies would have purchased a French still (of which only three were made) at the height of the Napoleonic wars (let alone been able to import it). As mentioned in part one, Edouard Adam (1801) made an improvement to the simple still. He did so by adding fractionation to the batch still via a series of egg shaped vessels. Adam’s work was based on the work of Professor Laurent Solimani and the two would go on to jointly patent further improvements. There is no denying the similarly in principle to a pot still with multiple retorts but how the West Indies came to use the double retort is rather more nuanced and much more likely from a parallel bit of work of Joseph Corty.

In 1818, Joseph Corty developed a double “compound” still with the second still containing external cooling (similar to that of Pistorius). DT Shears & Sons of Bristol would acquire this design and these double stills proved to be of “such repute” that Shears would supply “numbers of them for the colonies, but particularly Demerara” – Wray (1848). Double stills of varying designs could also found in the West Indies, some notable examples include one at the Londonderry Estate in Dominica (built at the copper works in Barbados) and of course the one at Port Mourant still in operation today. These double stills are the forerunner of the pot/double retort in common use today in Barbados, Jamaica, Guyana, St Lucia, Grenada among others. Early retort stills carried external cooling heads, no doubt the influence of the original Corty Still.

Leonard Wray (family to the perhaps better known J Wray) in his seminal work – The Practical Sugar Planter (1848) – wrote:

“But of all the arrangements, I have never known any to surpass the common still and double retorts”

This was no idle boast, Wray had extensive experience including of the Stills of Cellier-Blumenthal, Laugier (another type of double still) and Coffey.

At this time double stills, single retort stills and double retort stills were all in use and each of these types were supplied by Shears of Bristol. Improvements would continue – attached is a single retort of Blairs, produced around the turn of the century with the open cooling head replaced by a modern condenser. Rectification heads would be added to retort stills in Barbados and Guyana but notably not Jamaica. You can find a rectification head on the Port Mourant double still in Guyana.

While there is little evolution in the simple batch (pot) stills of Scotland, Ireland or Cognac on the scale of that in the West Indies, there are some common improvements that have been adopted.
In 1802, Charles Wyatt patented the application of steam “tubes” to distillation instead of direct fired stills which avoids the burning the wash on the bottom of the still. Today almost all stills in Scotland are steam heated but even here the West Indians were the more progressive. The steam used in the Coffey stills was thought to destroy the esters and it would not be until 1887 before Glenfiddich installed a still with steam coils. Famed Jamaican chemist HH Cousins carried out research in Jamaica on the use of steam and found it superior. This resulted in a quicker widespread adoption in Jamaica of the steam coil over Scotland. The Americans would also be quicker to adopt steam distillation over direct fire. Famously today cognac must be distilled by direct fire.

“I am convinced from the results obtained at Shrewsbury estate in Westmoreland, that all home trade rums could with advantage be distilled in stills heated by a steam coil. Burnt rum should then be unknown. The fetish of the ‘direct fire’ that still lingers in the minds of Scotch whiskey distillers has no basis at all where Jamaica rum is concerned, since any excessive firing results in a most serious injury to the spirit produced”

H H Cousins, West Indian Bulletin, 1907

The earliest stills cooled the vapour by passing it through a simple worm (or coil). Originally this was solely atmospheric cooling but in 1771, German Chemist Wiegel invented the worm tub where the worm is placed in a tub into which cold water is continuously pumped. In 1825, William Grimble invented the shell and tube condenser which replaced the worm tub for cooling the distilled vapour. Barnard’s encyclopedic work on Scottish distilleries in 1887 shows they were widely in use by then. Today just a small minority of Scottish distillers use a worm tub and most rum producers in Anglophone Caribbean use shell and tube condensers. The shell and tube condenser proved superior because it cools the vapour markedly more slowly and this in turn has a significant impact on the copper’s catalytic effect in removing undesirable sulphur compounds from the spirit. As vigorous molasses fermentations tend to produce more sulphury components over other washes, the popularity and rapid adoption of the shell and tube condenser in rum is of little surprise.

Visiting the region you can see the culmination of this history with double retort stills (some with rectification heads) dominating the rum producers of the Anglophone Caribbean.

Part Three – Foursquare

The myriad of still designs from past is overwhelming. Nostalgia makes us believe there is something better that has been lost to time whereas the reality is that much of what was discarded was inferior to how we distill today. Innovations that did not deliver did not last. Evolutions that worked became the norm. Different spirit cultures evolved though the different routes that worked for them and the progressive rum distillation techniques may not have delivered for Scotch what they delivered for Rum.

By examining this brief overview of the evolution of distillation, everyone can better grasp what we do at Foursquare and why.

Our twin column continuous still is based on that design principle of separation of the analyser and the rectifier first developed by Coffey in the 1830s. Likewise it produces a spirit that complements rather than competes with the spirit produced by our batch still. However, unlike the classic Coffey still the still operates under vacuum pressure. Instead of our wash boiling at a little over 100°C, our wash boils at just about 80°C with the consequent marked improvement in spirit quality. The high suspended solid content of a molasses wash make this technological advance all the more rewarding.

Our two batch stills are the classic pot/double retort design as used throughout the West Indies from Grenada to Jamaica. A design developed in the first half of the 19th century, “unsurpassed” in the words of Wray. Our retorts feature cooling heads, a feature first developed by Pistorius (1817) and Corty(1818) and popular in the West Indies in the stills built by Shears. It was Simon Dore, great grandson of John Dore who suggested to us that we revive the use of cooling heads on retorts.

Apprenticed to John Dore were the Carter brothers who developed the Carter-Head, an evolution of the rectification heads found on Shear’s double still and Saint Marc Still of 1824. Loch Lomond operates similar rectification heads today. At Foursquare, we have our own evolution of the Carter-Head on both of our stills. We have incorporated in these heads the use of ‘nano copper’ surfaces. This was developed by the CREA Research Centre (University of Siena) in collaboration with Green Engineering. The practical effect of these copper surfaces is to improve the catalytic effect of the copper. In this way, the thermodynamic process is unchanged but the chemical effect is improved. That is to say, one nano copper tray has the catalytic effect of six trays but the rectification power of a single tray.

Our older batch still has steam coils but our new batch still features a twin system of steam coil and bain-marie. A bain-marie is a steam or water jacketed still developed in the 16th century but mainly used by alchemists. Today, several craft distillers use small stills heated via a bain-marie. The twin system provides the most consistent and even way of heating a batch still. A smoky flavour is a natural component of a peated whisky but a smoky flavour in rum is just bad distillation.

We also use the shell and tube condenser on our batch stills for its superiority over the older worm tube vapour cooling system. Sulphury, metallic, “petrolly” rums are not our style.
As a homage to all that that has been learned and incorporated from the past, the man door on our new batch (pot) still is from an actual cast as used by John Dore & Co Ltd.

There is another innovation on our latest batch still, probably the most ambitious of all. But we will wait till its proved in the field before revealing.

Big thanks to Richard for agreeing to allow me to collate this information….Stay tuned for the Six Part collected article “Yeast In Rum (or S. Pombe Revisited)”

© Steven James, Rum Diaries Blog and Richard Seale. Unauthorized use and/or duplication of this material, both written and photographic without the express and written permission from this blog/sites author and owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Steven James, Richard Seale and Rum Diaries Blog with appropriate and specific direction to the original content.

Compagnie des Indes St. Lucia 13

Its been a while, but I’m back with another independent bottling. Coming again from the stable of Compagnie des Indes single cask bottlings, this time the delicious Rum within is from one of my favourite producers, Saint Lucia Distillers.

For a little light background reading on Compagnie des Indes as a company you can have a look here and for info on the basics surrounding Saint Lucia Distillers you can look here…..and now that you’re back, we can continue.

Compagnie des Indes St Lucia 13 – 43% abv

CDI SL13 LabelTo kick things off, I’ve been told that every drop of this Rum is the product of Pot Distillation. It has seen just upwards of 5 years tropical age which gives it between 7 and 8 years in Europe, a similar level of European age as the quite excellent Compagnie des Indes Foursquare 16. There was something quite unique that the split in location did to that Rum and I hope that it also works here. There was an outturn of just 296 bottles in this cask (an ex-Heaven Hill barrel) and it weighs in at a not unsatisfactory 43%. The keen eyed among you may have also (if you read the linked articles) worked out the still that this Rum is from. As the John Dore 2 still was commissioned in 2004, the Vendome still was commissioned in 2003 and this Rum was distilled in 2002, it must by the process of elimination come from the John Dore 1 still. The interesting thing (for me anyway) seems to be the correlation between small pot stills (think the much fabled small capacity Rockley Still) and the production of really medicinal like aromas and flavours. As an obsessive of anything even remotely Rockley Still related, this really has me excited. Having been fortunate enough to taste both unaged and aged distillates from the John Dore 1 still on the recent Saint Lucia Distillers on Tour event, this assumption of a correlation between Pot Still capacity (John Dore 1 has a capacity of 1500 litres) and medicinal aromas and flavours appears, thus far, to ring true….to me anyway.

Tasting Notes

CDI SL13 Angle

In the glass: The Rum displays itself as a straw gold in the glass and getting your nose anywhere near it instantly gives you a real hit off sharpness and a kick of the signature medicinal note. This medicinal note is present in large quantities and it brings with it a sort of salty, briny smoke. More time with the glass reveals a slightly earthy, medicinal sweetness in the form of root beer. Once you power through this (and it does take its time) you’re rewarded with a hint of something fragrant and flower like…but no real punch of oak is present which surprised me for a Rum of this age.

In the mouth: Initial entry gives no real heat but it does lead with a light fragrant sweetness….this is however very short lived and soon gets muscled out of the way by a cutting dryness that rather strangely is carried on a lot of fragrant woody notes…more sappy than heavy oaky notes. In fact this fragrant wood is a total polar opposite to what the nose gave away…it is really dominant in the early stages. The fruit is there but it is more akin to fragrance than a taste being so light as it is. The mid palate is dominated by a light fragrant flower like quality, maybe elderflower but this soon succumbs to the powerhouse of a finish. The medicinal edge that I so love powers through into the medium length finish and leaves that drying quality in your mouth with a light fennel and celery taste that fades very slowly…

This Rum yet again helps to back up the fact that St Lucia Distillers really are able to produce something special. The character that is carried through into this Rum is astounding. It may be a little one dimensional to keep my interest over an evening and the whole medicinal thing is a real turn off for some people, but fortunately not for me. At around £68 a bottle it’s not the cheapest purchase and it’s not a Rum that I can drink in huge quantities in a single sitting and it is probably best served as a reference Rum. I was hoping for something to completely blow me away in the same way that the Berry Bros. St Lucia 11 sample that I was kindly sent by Wes did, and subsequently the Berry Bros. St Lucia 14 that I now own as a result still does. But this isn’t quite up to the task. Almost amazing, but certainly a worthy purchase. However, comment must again be made about Florent and his Compagnie Des Indes company which really is starting to spread its wings and make accessible some really great Rums.

3-0-star

© Steven James and Rum Diaries Blog 2016. Unauthorized use and/or duplication of this material, both written and photographic without the express and written permission from this blog/sites author and owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Steven James and Rum Diaries Blog with appropriate and specific direction to the original content.