[UPDATE! I have Arroyo’s birectifier glass laboratory still and I’m working with it as well as bringing to life other tests he used. I’m even working with someone to build an automation kit for operating the still (which otherwise takes two hours of active time.]
But what is this all about? Through a grant from the U.S. government Arroyo set out to do detailed studies of rum production and he created new techniques in fermentation that revolutionized how rum was made. Even in Jamaica, which is known for dunder pits and muck holes, the leading producer, Appleton, likely favors the Arroyo method. I’m sure if you are here, you already know a little about Arroyo.
Not much happened with Arroyo’s work until decades later because of the timing of WWII (this was explained in Rum: Yesterday and Today), but everything was given an update with Puerto Rico’s Rum Pilot Plant and those agricultural bulletins are mostly lost as well. The RPP works are a series of twenty something bulletins and are in both English and Spanish because of how they were funded by the U.S. government. These documents transformed how rum is made around the world and were supposed to be shared and accessible, but somehow they’ve become elusive and even the most serious PhD spirits researchers do not cite them in bibliographies.
I have collected probably all of Arroyo’s citations from the journals they were originally appearing in mostly courtesy the bibliography of the late John E. Murtaugh who was one of the great distillation educators as well as a significant contributing author to the Alcohol Text book. [I should also note that German globe trotting sugar technologist, Hubert Von Olbrich, also lists most of Arroyo’s original citations in his Geschichte der Melasse, 1970. He only misses a few.]
Arroyo R., Circular 106, Rum Manufacture, 1938
[This is a block buster paper which I translated from Spanish. It is possibly the single greatest short read on rum production any new distiller can do.]
Arroyo R. , Manzano M. Jamaica Type Rum in Puerto Rico. University of Puerto Rico, Agr. Expt. Station Report for 1937-38, p. 26-27; rev. : Facts about Sugar 35 (1940) , no. 4, p . 38.
Arroyo R., Marrero F., Haravidez L. Rum Types and the creation of new rum types from cane juice. Report University of Puerto Rico Agricultural Experiment Station, 1939, p. 43-44, rev. : Facts about Sugar 35 (1940) , no. 11 , p. 37.
Arroyo R. The Aroma of Rum : The influence of pre-treating the raw material. Revista agricultura industria commercio; Puerto Rico 32 (1940),
no. 2, p. 284-286; rev. : Facts about Sugar 35 (1940), no. 11 , p . 37.
Arroyo R. Dilution Problem in Rum Manufacture, Sugar 38 (1943), no. 7,
p. 25, 26.
[I haven’t requested this because he covers it so well in the 1945 text.]
Arroyo, R. 1945. Studies on rum. Research Bulletin
No. 5 (University of Puerto Rico, Agricultural Experiment Station, Rio Piedras, Puerto Rico), December. [I have this but have not shared it!]
Arroyo died in 1949 so a few of these would have published posthumously.