KOUMISS 163 



and dextrose and galactase are formed ; and, in the second place, 

 these sugars are fermented, and alcohol produced, thus : — 



(I) C,oH2oO„ + H,0 = C^Hi-A + CfiHi-A 



(Lactose) (Dextrose) (Galactase) 



(2) CgHiaOgJ (plus the saccharomyces, \ = 2C.2H6O + CO., 

 (Dextrose) \ or fermenting agent) J (Alcohol) 



Alcoholic fermentation of grape sugar, of cane sugar, or even of 

 starch, is, if we may so express it, precisely the same as that which 

 occurs here, namely, an inversion followed by a fermentation, the 

 sugar disappears, the carbonic acid gas escapes into the air and the 

 alcohol remains behind. 



Occasionally alcohol is present in the milk of a dairy, as a sort 

 of by-product accompanying lactic fermentation, and alcoholic 

 fermentation may, under exceptional circumstances, cause serious 

 trouble to the dairyman. But the chief illustrations of this fer- 

 mentation in milk are the well-known examples of the artificial 

 beverages known as koumiss (or kumiss, kumys) and kephir (or 

 kefyr, kefr), the former a fermentation of mare's milk, the latter 

 of cow's milk. Matzoon'^ and Leben'^ are two other examples of 

 similar changes. 



Koumiss is made on the Steppes of South Western Siberia and 

 European Russia, by nomadic Tartars.^ It is, as already stated, 

 a fermentation of the milk of the mare. But it is not a simple 

 process nor a single fermentation. There is first a lactic fermenta- 

 tion producing lactic acid, and secondly a vinous fermentation 

 resulting in alcohol. The former is produced by bacteria, the latter 

 by yeasts. In neither case is the process set up by a pure culture, 

 the general method adopted being as follows : A small quantity 

 of old koumiss is added to about ten times its volume of mare's 

 milk. The fermentation is conducted in small casks or vats fitted 

 with a stirring apparatus which is worked vigorously for the first few 

 minutes. Before the fermentation is complete the fluid is bottled 

 and an effervescent beverage thereby obtained. The object of the 

 maker is, of course, to encourage the vinous or later fermentation, 

 and check the lactic or earlier fermentation. Mare's milk contains 

 less casein and fat than cow's, and its lactose favours lactic 

 fermentation more readily than cow's milk. For this double fer- 



' Centralb.f. Bakt, 1898, ii. Abth., iv. 418. 

 ^ Ann. de VInst. Pasteur, 1902, xvi. 65. 



3 See works by Carrick, Reynolds Green, Dochmann, Rothschild, Rubner, 

 etc. 



