Jamaica Association of Sugar Technologists (J.A.S.T.) Journal

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Jamaica’s response to the works of Rafael Arroyo were known to be published in the J.A.S.T. Journal, (Jamaican Association of Sugar Technologists) but for a long time they were inaccessible. What secrets did they hold? These were all unearthed by the incredible work of blog friend Yves Cosentino. He was even able to see the physical journals and retrieve articles beyond the few citations I had!

Jamaica rum is a messy topic and which gets sticky as they try to update a Geographic Indication (GI) for their rums. Not all of Jamaica rum’s production techniques are known clearly and there is a possibility that reputation relied on a few production ideas that were not widely practiced. Big open questions remain.

What was the frequency of occurrence of Schizosaccharomyces Pombe fission yeasts in Jamaican rum production? A century of rum literature portrays fission yeasts as queen of all yeasts and foundational for true heavy rum.

When Jamaica rum received its most esteem world wide, (alongside Batavia arrack), a defining feature may have been the near exclusive use of fission yeasts and this is highlighted extensively in the works of Percival Greig, Charles Allen, S.F. Ashby, and H.H. Cousins. Jamaica at one point in time even had a yeast service that delivered freshly prepared Pombe starters to distilleries at the beginning of the season. Somehow, possibly due to WWI, a generation gap developed and much of this work was forgotten. One JAST commentator specifically notes the work of Greig taking place nearly 50 years earlier. The work of Cousins likely ended in the 1920’s. This startling photo by Ashby is from 1909.

By the 1940’s, as revealed in these documents, there is a realization that they have drifted beyond the old style of rum production. This mainly comes from seeing the works of Arroyo which were highlighting fission yeasts for their ability to produce more esters while simultaneously producing less fusel oil. Fission yeasts may have still been in use at Hampden, Vale Royal, Georgia, Kew, and Cambridge. These distilleries however, had productions that appeared to be as small as a barrel a day and did not feel the need to represent themselves in the JAST works. These producers may have operated successfully knowing how to harness these yeasts (likely always with cane vinegar), but never knowing very specifically what was doing the work.

At some point in these papers we encounter young scientists enamored with Rafael Arroyo. There is even incredible discussion of having Jamaican producers license Arroyo’s patents and the potential establishment in Kingston of an office where Arroyo’s team would prepare yeasts. All this discussion happens through a Panamanian intermediary who had success using Arroyo’s patent. Jamaica could have been back on track with widespread use of Pombe yeasts, but then nothing materialized.

One detail that pops up in that discussion is Jamaica describing dunder as a signature of their process which Arroyo did not use. Arroyo acknowledged that his process could be adapted to use with dunder. The main significance of this note is Jamaica clearly defining their process in the documents. They yearned to return to their heritage of Pombe yeasts and acknowledged dunder as a part of their identify. If this was taken seriously it would likely complicate a GI.

Even in the 1940’s, Jamaica appeared to be pot still only, and as evidenced in JAST, differentiated between rum (pot still and dunder) and alcohol (anything else). Continuous columns crept into Jamaica for a variety of reasons. Heritage at the time, was not as critical to sales as it is today and they needed to process molasses that was piling up. They also needed to explore fuel ethanol production as an outlet for molasses in years following those where rum did not sell.

At present, we see both a decline and return to heritage as well as emergence of a grey area where few still know what happens in between. One great JAST article on the Rum Pool shows the importance of high ether grand arôme rums increasing. There is the possibility that it became more common to make middle weight rum from grand arôme concentrates cut with domestically produced continuous column spirit than to make middle weight Wedderburn style rums from single ferments run through pot stills. As light rums became fashionable, they were produced from heavier rums that were extensively blended down. Arroyo was actually the first to produce true light rums from a single ferment and not by blending.

Geographic Indications are designed to protect things. At the most fundamental level, they protect agriculture so they must be inclusive and truly understand their responsibilities. They are a tool for fragile subsistence industries and serve those at the bottom, not those at the top. The point of agriculture is not to produce abstract commodities that only get tallied by accountants, but rather to feed farmers. You don’t guard or protect rum, you protect those workers who live from rum. At the same time, special subsets of GI’s should exist to protect and exhibit great achievements within a sector. Jamaica should have classifications developed for its grandest traditions such as fission yeast rums featuring dunder, bacterial complications and pot distillation. As a rule, marketing should lead with these achievements. These rums have also traditionally been built as blending stocks relied upon by the entire world. Jamaica should develop a hosting and access framework where traditional blending outside the country can take place but in a transparent way that flatters and elevates the status of Jamaica (a lot more could be said here).

With fission yeasts being left as an open question and a future path for investment in rum production unknown, all discussion of updating a GI can be considered premature and possibly even naive. There is the growing chance that the West Indies may have to compete against their own abandoned heritage practices being executed elsewhere.


This is a lengthy blockbuster paper which gives a startling year by year description of the consolidation of Jamaica rum production in the years after the heyday of Cousins, Allan, Ashby and the original Experiment Station. We see detailed year by year figures of who produced what in terms of styles as well as how much continental grand arôme rum was produced each year.


This contains an amazing discussion of Arroyo that starts on page 10. A chief distillery engineer from Panama describes his experience with Arroyo’s patented process. There are some fascinating notes on the steam consumption of pot stills.

JAST 1946 vol 9 no 3-4 pp45-68 46-47 missing

I highlighted a paragraph about fission yeasts on page 9. They cite the old literature of Greig and Allen plus the new literature of Arroyo. Rum oil is referenced on page 13 and connections are drawn again from the old Jamaican works of Greig and those of Arroyo. Page 14 proposes further research that never appears to materialize and an extensive bibliography is presenting showing Jamaica was aware of a lot, but apparently not in a position to act at the time.

JAST 1947 vol unknown pp 45-59 Barbados disc PR visit Pot Still Exp

There are some interesting pot still experiments and disclosures that they don’t always know precisely what is happening. During the Puerto Rico visit, many rum distilleries were producing fuel ethanol at the time, which no doubt influenced Jamaican adoption of continuous stills as a hedge against bad years for rum.

JAST 1948 Steam Consumption of Pot Still vs Boiler Output

Simple experiments that are no doubt still very familiar today.

JAST 1948-50 vol unknown Milling Diffusion Process for Cane pp 33-38

JAST 1948 vol 12 pp 42-47 Induced Fermentation in Rum Stretton

I thought induced fermentation would be about spontaneous fermentation, but sadly, it is about using Fleischmann’s bakers yeast which is surprising for 1948 where others islands had already started experimenting with higher performance pure cultures. Don’t forget, forty years earlier, Jamaica had a yeast service organized by the Experiment Station.

JAST 1948-50 vol unknown Modern Trends Distillery Practice McFarlane plus Dunder discussion

In this paper McFarlane introduces Jamaica to modern trends and Arroyo’s name is mentioned 25 times and this is 4 years after the first attempt at introduction. An extensive bibliography is presented showing that all of Arroyo’s papers were collected. Many patents are also listed.


Bybrook presents their very simple improvements such as a calandria for heating.


This is another version of the first JAST paper I ever found and ends our series. It is 1959 and Jamaica rum stylistically is in a bit of a sorry state. Knowledge of Pombe fission yeasts that defined Jamaica rum’s reputation is slowly fading into obscurity. There are some observations in here that would definitely inform a GI discussion.

While we had access to these papers, it seemed wise to collect as much literature on dunder disposal as possible.


JAST Dunder Disposal 1944


This is an important paper because it shows various experiments with starting an anaerobic digestor. On page 11 they try the putrefying pit liquid from the Cambridge distillery. This distillery was small like Hampden and only produced a heavy continental style rum. In 1948, the Cambridge production was consolidated into Long Pond. My best guess is that this is where the Jackfruit tradition comes from. It was a sort of vegan anaerobic digestor and the knowledge was only spread when the production was moved. We cannot know for sure, but this is the highest probability clue we have. The next way to strengthen the idea would be to see from present knowledge if the idea emerged from Long Pond.

JAST 1947 Dunder Disposal


Barnett – Notes on Jamaica Rum 1951

I collected this many years ago courtesy a professor at the University of the West Indies.

1951 HARPERS WINE & SPIRIT GAZETTE History and Nature of Rum

A beautiful education on rum aimed at hotel workers. It tries to emphasize rums differing by fermentation rather than distillation.

United Rum Merchants Lemon Hart Lambs 1951 brochure


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