632 MICROBIOLOGY OF ALCOHOLIC FERMENTATION 



sources are used and any fermented beverage will, by distillation 

 produce a potable spirit varying in character and quality with the 

 source. Industrial alcohol may be made from any substance capable of 

 undergoing alcoholic fermentation, the'limiting factor in practice being, 

 principally, the cost of the raw material per unit of alcohol. 



METHODS 



PREPARATION OF THE SUGAR SOLUTION. Saccharine Raw Materials. 

 When spirits are to be made from grapes or other fruit, the juice is fer- 

 mented in the same way as for the corresponding beverage and then 

 distilled. The juice, however, is diluted to 20 Bal. or less-, as it is not 

 necessary or desirable to have too much alcohol in the fermented 

 liquid. The product is consumed directly as brandy or used to fortify 

 sweet wines. The principal fruits used besides grapes are apples, 

 peaches, plums and cherries. 



Industrial alcohol has been made from inferior or spoiled fruits and 

 from cannery wastes, but the cost per unit of alcohol is usually high. 

 The difficulties of fermentation are great, owing to the presence of large 

 quantities of molds and other injurious organisms, and the extraction 

 of the juice is troublesome. A careful use of sulphites and pure yeast 

 much simplifies the process. 



Sugar cane and its products are used in several ways to produce alcohol. To a 

 limited extent the juice of the cane is fermented directly and distilled. The product 

 is known as Jamaica rum. Much larger quantities of alcohol are manufactured from 

 the cane-sugar molasses and appear in commerce as rum, taffia, arrack or neutral 

 spirits. 



For the making of Jamaica rum the juice is pressed from the crushed canes, and 

 diluted with 20 per cent of vinasses (the residue of a previous distillation) to increase 

 the acidity, and give the required flavor. 



Cane molasses which contain from 50 to 60 per cent of fermentable sugar are 

 diluted with water or vinasses to i5-i8Bal. and partially neutralized with lime 

 when the acidity is excessive. 



One of the principal sources of industrial alcohol is the sugar beet. This alcohol is 

 also used for the adulteration or imitation of potable spirits. 



It may be made by the direct fermentation of the beet juice, extracted by grinding 

 and pressing, by methodical maceration or by diffusion. Sulphuric acid is added 

 during extraction. This facilitates the extraction by setting free organic acids, and 

 represses the growth of injurious microorganisms. The amount used should be such 

 that a minute quantity of sulphuric acid remains free. 



Most beet alcohol is made from the coarser molasses of the sugar factories. The 

 molasses are diluted to 2o-3o Bal. with water, further diluted and heated with 



