FERMENTATION 



5/1 



yeast mash which had been treated in the way described above, this quantity 

 being found sufficient to prevent the development of injurious organisms. 



Pure Yeast Processes. — In the processes described above the fermentation 

 takes place under the influence of such yeast moulds and bacteria as adven- 

 titiously find their wa\^ into the wash. Bj- a pure yeast process, is meant one 

 in which the fermentation is conducted under aseptic conditions, and under 

 the influence of one selected yeast. Such a process in its entirety demands 

 the sterilization of the raw material, and the continued cultivation in special 

 apparatus, designed to prevent contamination of the selected j'east. The 

 sterilization of the wash is not absolutely essential to the process, as sufficient 

 of the pure 3-east ma\^ be added to ensure that the fermentation takes place 

 mainly through it. Pure yeast processes are in very limited use in the cane 

 siigar industry, and the only plants of which the writer has knowledge are 

 in the state of Morelos, in Mexico. The process here followed as described 

 by Fournier-^ includes a Magne apparatus for the aseptic continuous pro- 

 duction of selected yeast, two intermediate vats of 25,000 litres capacitv each, 

 the contents of which are " pitched " ^^•ith the pure yeast, and which in turn 

 serve to supply 3'east to the main fermentation vats of which there are 

 forty-five of capacity 17,000 Utres each. In such a process by means of 

 selection, yeasts capable of completely fermenting wash at a density of i • i 

 can be used and 3ields 95 per cent, of the maximum possible can be obtained. 



Rum. — Rum has been legall}^ defined in Great Britain as a spirit distilled 

 from fermented products of the sugar cane in a countr}- where the sugar cane 

 is grown. This definition is quite inapplicable to the United States, where 

 rum has been manufactured in New England from molasses since the old 

 colonial da3's. It is also almost self-evident that the location of manufacture 

 need have nothing to do with the composition and flavour of the product. 



Originally the term rum was confined to a spirit distilled from juice, the 

 term tafia being used for spirits of molasses origin. The term in the French 

 West Indies is guildive, a corruption of " kill devil." 



Rum consists mainh' of alcohol and water, the other bodies present 

 being caramel (in coloured rums), fatt3^ acids, ethereal salts, aldeh\-des, 

 higher alcohols and essential oils. The acids kno\^^l to be present are 

 formic, acetic, but3Tic and capric, both free and as ethereal salts. 



Miller^' has given the following anah-ses of Demerara rums : — 



ANALYSES OF DEMERARA COLOURED RUMS. 



Percentage by Volume. 



