JAMAICA. 



BULLETIN 



OF THE 



BOTANICAL DEPARTMENT. 



New Series.] AUGUST, 1895. 



A CONTRIBUTION TO THE STUDY OF THE PRO- 

 DUCTION OF THE AROMA IN RUM. 



By Percival H. Greg. 



This account of some experiments which I have been making in this 

 direction, and which I venture to submit to readers of the Bulletin in 

 general, and to Planters and Distillers in particular, pretends to be 

 simply what it is entitled — a contribution — the question indeed is a 

 wide one and may be approached from many sides. 



The aroma of rum may be said to bs mainly due to five causes, 1st 

 the nature of the plant from which rum is made, the sugar cane ; 2nd 

 the soil on which it is grown ; 3rd the fermentation ; 4th the distilla- 

 tion ; and 5th the storage in cask, at the high temperature prevalent in 

 the tropics. My researches as will be seen, deal exclusively with the 

 aroma developed during fermentation, with special regard to the in- 

 fluence exercised in this direction by a particular variety of a peculiar 

 type of yeast. They were suggested to me by the brilliant results 

 attained by Prof. Hansen in his employment of pure yeast in the 

 manufacture of beer. Following out Prof. Hansen's ideas as to the great 

 influence exercised by the type of yeast on the nature and resulting 

 products of the fermentation, my work at first consisted in isolating 

 and cultivating pure, according to Prof. Hansen's method, as many 

 different varieties and species of yeast, as I could obtain from the 

 materials, molasses and dunder, sent to me from Jamaica, and institut- 

 ing with such cultures trial fermentations on a small scale. I gave a 

 preliminary account of these researches in the " Sugar Cane" of Nov. 

 1893, in which I stated that I had isolated a considerable number of 

 varieties of Jamaica yeast, possessed of very different properties. 



One yeast in particular seems to me to have a special bearing on the 

 production of the aroma in rum. It belongs to the type known as " top 

 fermentation" yeast, i. e., it throws up a " head" on the surface of the 

 fermenting liquid, which, in molasses and dunder, is of a beautiful 

 golden colour and very tenacious in character. The progress of the fer- 

 mentation is a slow one, varying, according to the composition, concen- 

 tration and temperature at which the wash is fermented, from 10 to 14 



Vol. II. 

 Part 8. 



