TYPES OF BACTERIA FOUXD IN MILK 



the Arabs from mare's milk, which will undergo an alcoholic 

 fermentation; but now an imitation product is widely made and 

 used, prepared from cow's milk. A small quantity of sugar is 

 added to milk, and some common baker's yeast. An alcoholic 

 fermentation soon begins, 

 and the fermented prod- 

 uct is kummys. Various 

 modifications of this gen- 

 eral process are adopted 

 by different makers, for 

 kummys has become a 

 commercial article. 



Several other alcoholic 

 beverages, in different 

 countries, are made 

 special methods from 

 cow's milk. 



The first of these to 

 which attention was given 

 is kefir, a beverage long 



known in the Caucasian mountains, and produced from or- 

 dinary milk by adding some bodies, called kefir grains. 

 (Fig. 27.) These grains have been in the possession of the 

 people from time immemorial. They are placed in milk, where 

 they soon produce a fermentation. After the fermentation is 

 over, they are removed and used in some more milk, or, per- 

 haps, they are dried for preservation for future use. Kefir grains 

 consist of a mixture of several kinds of bacteria and of yeasts. 1 

 The nature of their action is essentially a doubk one. The 

 bacteria have, first, a chemical action upon milk sugar, convert- 

 ing it into a type which is easily fermentable by yeast, and the 

 subsequent alcoholic fermentation which occurs, is due to the 



FIG. 27 KEFIR GRAINS 



1 Freudenreich. Land. Sahr. d. Schw., 1896. 



