Rum Historian by Marco Pierini
HISTORY OF CUBAN RUM
11. BEFORE PASTEUR
The World of Rum is a vast and well-established reality, which withstood the restrictions caused by Covid 19 and fully recovered as soon as the pandemic came to an end. It is enough to know it a little to realise that this world is fascinated by distillation and ageing techniques.
It is no wonder, distillation is a fascinating art which has its roots in Alexandrine alchemy (see my series “THE ORIGINS OF ALCOHOLIC DISTILLATION IN THE WEST” in the 2018 issues), a shining example of human intelligence capable of modifying matter, but also an intriguing mystery. Moreover, alembics and stills are often very beautiful artifacts.
Not to mention ageing! Many become poets and dedicate true and proper love poems to barrels. This shouldn’t surprise us either, wine cellars are usually gorgeous, bewitching places with their rows of barrels where rum sleeps the sleep of the just in the semi-darkness of vast spaces, maturing slowly until the magical moment when the Rum Master decides that, at long last, it is ready for consumption.
Fermentation, on the other hand, does not arouse much interest. Admittedly, it is not nearly as spectacular. The sight of a fermentation tank may thrill us rum geeks, but frankly, truth be told, it’s not much to look at. The great tanks of modern industries tell us little. Besides, let’s face it, the smell is not the best. And yet, we know that fermentation is decisive for the “construction” of a good rum. Distillation, in fact, concentrates and selects, ageing refines and improves, but the foundation of rum is what was produced during the fermentation.
Historically, fermentation is the last phase of the rum production process to have achieved the status of science. For centuries, planters had known that something happened in the fermentation tank, the continuous formation of bubbles, the heat and the smell struck their attention, often they referred to it as if it was something alive. Over time, Caribbean planters even learned how to intervene, adding or removing substances and heat in order to get a better result. But it was always a rule of thumb, though; nobody knew what really happened in the tank.
From this point on, I rely on Ian S. Hornsey “Alcohol and its Role in the Evolution of Human Society” published in 2012. Unless otherwise specified, all the quotes are from this book.
“From the earliest of times, natural philosophers have been fascinated about the seemingly spontaneous change that transformed grape juice into the physiologically interesting beverage called wine. Fermentation, although not understood, was an important entity to the alchemists and formed a core of many of their ideas (as did putrefaction, which they appreciated was a separate process). Ideas relating to the exact nature of fermentation were highly confused until the second half of the 1600s, when scientists realized that only sweet liquids could give rise to true fermentation.”
The first to discover the existence of microorganisms was the Dutch scientist Antonj van Leeuwenhoek (1632-1723) from Delft. He disseminated his discoveries in the scientific world of that time, thanks also to a rich exchange of letters with the Royal Society in London. But “For whatever reason, systematic study of microbes was delayed for another 100 years or so, and it was not until 1786 that the Danish zoologist, O.F: Müller, studied bacteria and succeeded in discovering details of their structure. … Yeasts from different environments were described, in some detail, but it was not until 150 years later, in 1826, that Desmazières described the elongated cells from a film of growth on beer.” Anyway, he said nothing about fermentation.
“When one considers that microbes were first observed some 350 years ago, it is difficult for us, in our modern world, to understand how it took around 200 years, until the time of Pasteur, to attribute unequivocally the phenomenon of alcoholic fermentation to the humble yeast. The religious atmosphere during those years was such that any doctrine other than spontaneous generation (abiogenesis) was unacceptable and prevented the promulgation of heretic notions that a minute organism, such as the yeast, might be responsible for fermentation.”
“Spontaneous generation dominated some areas of scientific thought during the eighteenth century, and it was not until the publications of Pasteur that it was laid to rest.”
“The proposition that yeast was a living organism, not a chemical compound, was not made until the mid-to late-1830s, when the results from three totally independent pieces of work appeared. It should be emphasized that these treaties coincided with the development of much-improved microscopes”
But “All three pieces of work were criticized, and even derided by the scientific establishment of the time.”
Only in the 1860s did Louis Pasteur put an end to the debate and determine the origin and function of yeast in alcoholic fermentation: “Alcoholic fermentation is an act correlated with the life and organization of the yeast cells”. That is, fermentation is a biological process and not a chemical one, as many scientists (and planters) thought. A synthesis of most of Pasteur’s conclusions was later presented in his two classic works: “Etudes sur le vin” (Studies on Wine) published in 1866, and “Etudes sur la bière” (Studies on Beer) published ten years later, in 1876. “… he established unequivocally: 1) the role of yeast in ethanolic fermentation, 2) fermentation as a physiological phenomenon and 3) difference between aerobic and anaerobic utilization of sugar by yeast; indeed, pasteur invented the terms ‘aerobic’ and ‘anaerobic’.”
And yet … Science is a work in progress and later research dimostrated that things were more complex. Let’s read what Richard Seale writes in his series of articles “Yeast in Rum (or S. Pombe Revisited)” posted in RUM DIARIES BLOG, February 15, 2021. “Ultimately neither scientist was entirely correct or entirely wrong. Edward 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 a collection of enzymes. So alcoholic fermentation is after all a bio-chemical process. Buchner published his work in 1897 for which he was awarded the Nobel prize.”
Cuban Manual
Let’s now read the “Manual de la fabricación del aguardiente de caña” (Hanbook of rum making) by Leopoldo García Ruíz, published in Santiago de Cuba in 1855. On the basis of his practical experiences and his theoretical knowledge, the author aims to summarize and present the state of the art in rum making. It is 1855 and in Cuba the study of rum making was highly developed and the pursuit of quality pressing. But regarding fermentation, they still played it by ear. I was frankly astonished by the limited and vague knowledge they had at the time; man had been fermenting for millennia, yet about the nature of fermentation ignorance reigned supreme.
The chapter dealing with fermentation is entitled Agentes de la fermentacion (Fermentation Agents). It begins by emphasizing the need for air and heat, and so far so good – more or less; it was quite clear that, for the fermentation process to start, the tank had to be exposed to air, and there had to be heat, and generally in the climate of the Caribbean the warmth of the environment is sufficient. It was also known that, for fermentation to take place, there has to be el dulce (the sweet) in the tank, but that was about it. The Manual dwells on two fermentation agents which can’t fail to impress us today: electricity and the so-called fermento (ferment), the latter being the main fermentation agent, according to the author. Here is what he writes:
“ELECTRICITY - We can say little of this fluid, despite the so important role it represents in fermentation, because, mysterious of itself, and not well known its properties in nature, it is consequent that its effects must be dark and difficult to explain. In my view, therefore, this is the mysterious part of fermentation, and in that it is impossible to explain certain phenomena which usually occur without apparent cause being found to produce them. We do know that an agent of fermentation, that when the atmosphere is loaded with this fluid sometimes happens to upset the fermentations and quickly pass to the state of acidity; but we do not know how this happens, nor do we reasonably explain this phenomenon. It is also generally believed that the effect produced by the ferment on the fermenting liquid is due to this fluid; but no one has explained how it works. So we recommend only that the fermenting barrels are outside the influence of a strong current of this fluid, trying to isolate them as much as possible, and that they are not in contact with bodies that are good conductors. I do not think that we should be working in this industry at the station where the atmosphere is charged with electricity, because it could disrupt operations and completely disorient the manufacturer.
FERMENT - We have come to the explanation of the most important agent of fermentation: effectively the role it represents is the most interesting, because that characterizes this operation. I will therefore try to explain what is generally accepted, but not how it acts; because, in reality, this has not yet been satisfactorily explained.
The ferment is, therefore, an azoate matter that results from an alteration of the gluten and of the vegetable albumin, that is not operated but to the contact of the air and that the fermentation itself favors.
It follows that a fermenting liquid containing the said two bodies in abundance will also produce abundance of ferment during fermentation, which in turn as it is formed will work on the same liquid. It is necessary not to lose sight of this principle in our manufacture of rum; because when operating on molasses that contain enough gluten and some vegetable albumin, an equivalent amount of ferment is generated, so to say, which means that we do not need in them a special ferment, for we are satisfied with what is produced in the same fermentations. But as it is always necessary that some quantity, even small, comes into play to excite the first movement of effervescence, it will be understood that the part contained in the barrels that have already made some fermentations will be enough to achieve the objective; and when there is no barrel, in this case either a bundle of bagasse of cane may be used, known by its vinous smell to be undergoing fermentation, and that by means of a weight is introduced to the bottom of the barrel or by some buckets of some wash that is at its maximum of effervescence, or the thick foams that rise to the surface before the wash reaches the tumultuous fermentation.
The property that the ferment possesses to determine the fermentation of a sweet solution is very fleeting, only some alterations suffice to remove this faculty completely. Among others, which I do not quote in order not to exceed the narrow limits that I have proposed to myself in this work, the boiling for more than ten minutes makes this agent lose its fermenting power and reduces it to nothing in this sense. Keep this well in mind, as a principle, to draw from it the deductions that correspond.
I will not conclude this chapter without making an important observation, that is, that the part of ferment that works in the operation, is about two percent of the sweet employed; so that if there is more than this quantity in the liquid, it will be unnecessary and useful if it is collected, before distilling, to use it for other fermentations; and if there is less, it will not enter into fermentation other than the part of sweet corresponding to the ferment that exists in the liquid, leaving the rest without fermentation, and therefore without breaking down. But as we have said that our molasses contains enough gluten, and even more, to produce the necessary fermento needed in our operations, this last case will not take place, unless these have suffered some alteration or the operation is badly done.
If the excess ferment is to be used in the operations, it must be understood that it exists in the sediment accumulated at the bottom of the casks after fermentation has been completed.”
If some passages of the text seem obscure, don’t worry, indeed they are, at least for me, even in the original language. It is, however, an important document; it shows what was known about fermentation in Cuba (and not just in Cuba) immediately before Pasteur’s discoveries.
Last, but not least, the author tells us that also guarapo (cane juice) was poured into the fermentation tank together with the molasses, and that the whole fermentation process lasts up to 7 days. Two surprising pieces of information, which produced a kind of rum very different from what Cuban rum would be within a few years and to this day. We’ll get back to this.
-written by Marco Pierini-
