Arroyo – The Production of Jamaica Type Rums in Puerto Rico, 1940

Arroyo R. La Fabricacion de Rones del Tipo Jamaiquino en Puerto Rico. Revista agricultura industria commercio; Puerto Rico Vol. 32 (1940) 131-134

The Production of Jamaica Type Rums in Puerto Rico

Por Rafael Arroyo, Ch. E. & S. E.,
Especialista en Fermentaciones Industriales; Jefe División de Química Industrial de la Estación Experimental de la Universidad de Puerto Rico.

It is our purpose to demonstrate that Puerto Rico could manufacture Jamaican type rums and enter competition with Jamaica not only in the limited market of the United States, but in the world market. These are not cheap imitations of the excellent rums that have made Jamaica famous around the world, but the making of rums that are indistinguishable, even for experts in the field, from genuine ones produced in Jamaica for export purposes.

In the presentation and development of the topic, divide it into three parts. The first will describe the manufacturing method used in Jamaica for export rums, according to the consensus of the literature we have obtained on the subject. The second one will expose the method that, according to our studies and research, we could put into practice on this island. The third part will outline the general advantages that would be on our side.


The batición is prepared in a variable way according to the established practice or taste of each distillery; but in general it comprises the use in very varied proportions of the following materials:

1. “Skimmings”: this term includes the foams of guarapo boilers in defecation processes; of molasses and syrup foams; wash waters from the boilers, etc., etc.

2. “Dunder”: the “dunder” is equivalent to the liquid of the fermented batición after it has undergone the separation of the ethyl alcohol and other volatile bodies during the distillation. It is used fresh or after being subjected to a secondary bacterial fermentation.

3. Cane molasses: end molasses are generally used similar to those of Puerto Rico, except that they usually have a higher content of total sugars.

4. “Muck-Hole Material”: the description of this material is somewhat complicated. The distilleries (which are usually attached to the sugar mills) have a so-called waste and acidification cistern, where the “muck-hole material” is prepared, and this tank is used for bagasse, cane straw, “skimmings,” dunder “, fermented cane juice, limestone powder, tank washes, boilers, evaporators, defecators, etc… etc. This mixture enters in prompt fermentation, with profuse development of organic acids, esters, innumerable bacteria and fungi. A certain amount of this material is incorporated into the batición when it has entered into vigorous alcoholic fermentation, otherwise the distiller would be exposed to completely inhibit the development of the yeast.

5. Water: variable amounts are used as diluents of the mixture described above until achieving the required degree of density.

As we said above, there is no fixed rule regarding the proportional amounts of each of the ingredients of the batición. Each manufacturer follows their method according to their previously acquired experience with leagues of different proportions. As an example of the specific preparation of one of these baticións we will quote the following:

“Skimmings” —————-620 gallons
“Dunder”——————–760 gallons
“Muck-Hole Material——-220 pounds
“Finaly Molasses————200 gallons
Water — Sufficient to reduce the liquid density to 25 degrees Brix.

The fermentation of this batición is laborious and prolonged and the unfermented sugars are always high. The fermentation usually lasts from seven to ten days, and after it ends it is customary to give a period of rest to the batición that varies between one and three days before being subjected to the distillation process. The original density of the batición that we noted was around 25° Brix, will have dropped to 12° after the fermentation finished. The alcoholic yield, based on absolute alcohol, will vary between 30 and 35 percent over the weight of total sugars in the batición.

The fermented batter is distilled in different ways according to the aromatic degree, aromatic persistence and quantity of esters that you want to obtain. In the case of the rums destined for export to Germany, the distillation takes place in two stages in stills devoid of rectifying columns, making use of the redistillation as a means of rectification. In this way, distillates with large contents of esters are usually obtained.

From the above exposed on the manufacture of export rum in Jamaica we can deduce that:

1. The composition of the batición is complicated and annoying.
2. The fermentation of the batición is too long and inefficient.
3. Very poor commercial performance.
4. The manufacture of the product independent of the sugar factory would be doubly difficult.


The studies and investigations that we have carried out in this laboratory on the manufacture of Jamaican-type rum, have shown us that this kind of rum can be manufactured in Puerto Rico by entirely scientific methods, based on pure cultures of yeasts, bacteria and fungi. The different types of rums would be products of variations in fermentation and distillation technique; but it would not depend on the products of a “Waste Cistern”.

In our case, the raw materials that come into play in the making of rum would be:

1. Regular final molasses.
2. Water.
3. Nutritional material for the yeast (only in terms of supplying deficiencies in the molasses).
4. Calcium hydroxide.

As an example of the preparation of a batición we will give the following:

Final Molasses ———- 1,000 kilos
Water ——————–5,000 kilos
Nutritional Salts ———According to the deficiencies of the final molasses.
Calcium Hydroxide——-In sufficient quantity to obtain a pH value between 5.8 and 6.0 in the batición.

The batición thus prepared would be heated to 80 degrees centigrade for one hour; cooled quickly and inoculated with a special pure yeast seed. After a certain time, which would vary, depending on the yeast between zero and 14 hours, the selected seed of pure bacteria would be incorporated to work in symbiosis with the yeast used. And that would be all.

The fermentation would be finished in a very reasonable amount of time, between 30 and 48 hours, according to the yeast selected for the fermentation. It would then be optional to give it 24 hours of rest before proceeding with its distillation. Which means that instead of seven to ten days as in the case of Jamaica, we would have our batición ready to be distilled in a period of time that would vary between 30 and 72 hours.

For each yeast used, we would have practically constant commercial rum yields. The numerical value of these yields based on weight in absolute alcohol compared to weight of sugars in the batición, would be between 42 and 45 percent; that is, each hundred kilos of total sugars would yield us from 42 to 45 kilos of absolute alcohol; which would yield an increase of 10 to 15 percent over the yields obtainable under Jamaican conditions.

These rums would be distilled in discontinuous distillation apparatus; but with the necessary variations of technique to obtain the most desirable product in each case.


A comparative study regarding the technique followed in Jamaica for the manufacture of export rums and the method recommended for Puerto Rico yields the following significant data:

1. The method we would follow in Puerto Rico would be much simpler.
2. Fermentation would take place in 20 to 25 percent of the time spent in Jamaica.
3. Pure cultures of the different fermentative agents would replace the materials of the “Trash Cistern”, guaranteeing stability in taste, bouquet and yield.
4. The yield in commercial rum would be between 10 and 15 percent higher than the currently realized in Jamaica.
5. The manufacture of the rums could be carried out independently of the sugar mills.

In addition to these advantages inherent to the manufacture of the product in terms of method and technique, we have other no less apparent:

Our island has greater natural resources for large-scale production, our sugar industry being much more extensive and richer than that of the British Antilles. We also have the great advantage of the free entry of our rum in the United States. Therefore, once this new industry is conveniently fostered in Puerto Rico, we should not doubt that we could enter into open competition with the Jamaican industry, not only in the United States, but in the entire world, with the exception of England and its colonies. The Scandinavian countries, the Netherlands, Belgium, Germany, Switzerland, France and Hungary, could become some of our best customers.

But returning to the nearest and safest market in the United States, we find that between 500,000 and 600,000 gallons of Jamaica rums are currently imported between bottles and barrels. Without pretending to monopolize the total of these imports, but capturing 50 percent of them – would not it be a good business for us? Let’s see some figures.

There are, of course, different qualities among Jamaican export rums, as they exist among those produced by us; but we have been informed by houses dedicated to the business in the United States that the average price of a case of Jamaican quality rum fluctuates between $25 and $35, against $15 to $18 received by the best Cuban brands, and from $8.50 to $11 that is paid for ours. We refer to prices of importers. There is, however, a quality of Jamaican rum that is being imported into the United States at the beautiful sum of $14.50 a gallon, in barrels.

If the figures above are correct, we find that Jamaican rums are paid in the United States market at approximately triple the price of ours. Therefore, if our island could put rums on the market of the same quality as those of Jamaica at a cost practically equal to that which amounts to the manufacture of those that we currently produce, it is not necessary to enter into many calculations to prove that the net gains per case of rum sold would be at least double or triple what is now obtained.

We could well, looking at the business from another angle, lower the price of these rums in the US market and thus greatly increase their consumption. When we say that the consumption of Jamaican rums in the United States is insignificant compared to the Cuban type, we do not take into account that with what the consumer spends in a bottle of good Jamaican rum, he could buy almost two bottles imported from Cuba and three bottles from Puerto Rico. We manufacture Jamaican type rums of equal or better quality to those already well known as genuine Jamaican rums in the world market, and lower the selling price to the importer of $ 30 to $ 15 or $ 20 per case, and we will see the reaction of the consuming public.

The only objection of any weight that could arise to the idea presented here would be the doubt that in Puerto Rico a Jamaica type rum can be manufactured indistinguishable from the first quality produced there. Regarding this point, we must clarify that certainty could only be achieved by trying to produce these rums on a commercial scale; but we do want to point out that during our investigations on the manufacture of these rums we have had the satisfaction of showing to strangers that we have produced no less than three to four different types, all classified within the Jamaican rum class. These rums have been bottled after only two years of aging in barrels and have come out gracefully when they have been compared by German experts with genuine Jamaican rums of two and three times greater aging. These rums can be examined in this laboratory by any of our readers who so desire.

As a testimony of the above, we are pleased to copy the translation of the original in German from a letter received from a house importing Jamaican rums from Hamburg, Germany, in which they offers their expert opinion on samples of our experimental rums examined by their chemists and tasters compared to the rums they import from Jamaica for 80 years.

“Referring to your visit, we would like to thank you for the samples of rum you left with us for this test.

We are sorry that in the present it is impossible for us to import these rums from Puerto Rico, since we could not get permission from our government for that purpose, however, we have great pleasure in giving you our expert opinion on the rums left here by you:

The samples of your rums corresponded exactly in terms of richness of flavor and taste, as well as force, with the Original Rum of Jamaica that we import here. We get the impression that the rums represented by the samples in question must be old products of many years in barrel.”

(Fdo.) E. SPECHT & Co.

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