Rafael Arroyo – The Lost Preface to Studies on Rum

Over the years I have slowly collected all of the journal articles Rafael Arroyo published on rum production despite few citations appearing in bibliographies. In the beginning, I avoided Spanish language papers, but eventually I learned to be a better translator. It was slowly revealed that Arroyo published a series of short candid papers over many years that form a preface to Studies on Rum (1945). These papers all appeared in the Spanish language journal, Revista de Agricultura de Puerto Rico.

It is hard to capture how well written and accessible these short articles are (typically 2-3 pages). They show a much different side of Arroyo’s work which is not overly technical, but much more about creating demand and inspiring proper investment. At times, Arroyo goes into amazing sensory descriptions which are quite unique for the era. Many of these ideas never left the Agricultural Experiment Station in Río Piedras, Puerto Rico and are still only in our future.

One of the first reasons Arroyo’s rums never came to be is because of demand. Few people knew, on a sensory level, what was possible or what their organoleptic goals should be. How could you chase Jamaica rum if you had never tried one? Rums had reputations, but genuine examples were much harder to experience than you’d think. Many producers today, barely have experience with the product of other renowned producers.

The next thing holding Arroyo back is that rum was always in a boom and bust cycle. How do you invest in such a capital intensive business when the next year is a bust? Even during booms, volume took precedence over quality. Today, for capital, you’d need bio reactors (to grow yeast) that no one else seems to use because they all outsource to yeast houses. You’d need a centrifuge no one else seems to have (Westphalia type). Many new distilleries suffer from what I call “closed loan syndrome”. Because they didn’t know the full scope of what they needed, when their large initial loan is closed, they cannot raise even an additional thousand to adequately finish the project. You must know what you need in the beginning or you are doomed. That is hard when you are building something nearly unprecedented.

Lastly, in the 1940’s, analysis made in research papers differed markedly from what producers were actually capable of. Arroyo was abnormally brilliant and so were many other government funded researchers who also had high powered labs. Many of their methods never made it to the distillery lab. What strikes us today as casual descriptions of pH was anything but back then. Measuring pH in 1940 was arduous and expensive so instead titration was king. Nowadays, we use pH effortlessly and have forgotten how to titrate! Turns out you need both. Many producers today use $40,000 forms of GCMS, but do not know enough about interpreting the results or applying it to the design of quality improvement experiments (that also fit into their forty hour work week). Rhummeries are not progressive family owned wineries and no one lives on the estate that works around the clock.

The rums described in these papers are our future, but we certainly have hurdles to overcome and nothing will happen without proper visionary investment as well as high productivity teams that are all up on the reading.

The Birectifier In The Fair Evaluation Of Commercial Rums (1938)

The Aroma of Rum I (1939)

The Aroma of Rum II Adequate Yeast Selection (1939)

The Aroma of Rum III Influence of Fermentation Technique (1940)

The Production of Jamaica Type Rums in Puerto Rico (1940)

The Aroma of Rum IV Influence of the Raw Material Pre-treatment Process (1940)

The Alcohol—Temperature— PH Value Complex in Rum Fermentation (1940)

The Aroma of Rum V Influence of the Pre-distillation Treatment of Fermented Material (1940)

Old Rum or Mature (1940)

The Story Of Rum (Reprinted From Package Store Journal) (1940) [not Arroyo, but quite important]

The Aroma of Rum VI Influence of the Distillation (1940)

The Problem of the Ripening of Crude Rum (1940)

The Aroma of Rum VII Influence Of The Period of Maturation (1941)

The “Tufo” (stink) of Crude Rum (1941)

Practical Results of Our Research in Manufacturing Rum (1941)

Fusel Oil in Rums (1941)

Rum production is a massive topic filled with tangents. I’ve found it very challenging to even speak with distillers who have done little reading and are not versed with the wide world of rum. The preface these papers add up to is the most concise foundation of all future conversations on rum. After that, you go to Kervegant’s Rhum and Cane Eau-de-vie (now in English).

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