FERMENTED MILKS 



405 



For the preparation of kefir the grains are soaked in lukewarm 

 milk for two to three hours. The milk is then poured off and the 

 grains covered again with fresh milk, which process is repeated 

 four to five times. When the grains have swollen, sometimes to 

 100 times the original size, they rise to the surface, are skimmed 

 off, and added to freshly boiled milk. The milk is ripened at a 

 temperature of 14 to 18 C. for eight to twelve hours. The 

 product of this fermentation, "sakwaska," is passed through a 

 sieve or cloth, the grains are recovered, dried in the air, and 

 preserved for future use. The milk is placed in bottles for a sec- 

 ondary fermentation at 12 to 15 C., and as this second fermenta- 

 tion proceeds the milk becomes rich in alcohol and carbon dioxid, 

 and is usually consumed within three days. 



The fermentation is sometimes carried on in large containers 

 made of skin, and these are hung near a door so that passers-by 



Fig. 182. Masses of kefir grains: a, b, c, Dry grains; d, e, f, swollen grains. 



(Weigmann.) 



can agitate them by kicking, or children, by playing with them. 

 At the end of the ripening period a small portion of the skin bottle 

 is tied off with a cord and the bulk emptied out for use. The large 

 part of the bottle is filled again with freshly boiled milk, the 

 portion that was tied off released, and thus the fermentation 

 renewed. 



Kefir is also made by adding 1 part of ripe kefir to 3 to 4 parts 

 of milk and allowing the mixture to ferment for forty-eight hours, 

 with occasional shaking. 



Kefir is a thickly fluid, creamy, effervescent, alcoholic bever- 

 age. On standing, the casein settles, but shaking renders the 

 fluid homogeneous. There is little or no digestion of the casein 

 in fresh kefir, but in old kefir the casein may be partly dissolved. 



It is customary to use milk that is not very rich in fat for mak- 

 ing kefir, otherwise a rancid taste is liable to develop. 



The following analyses of kefir are given in Richmond's Dairy 

 Chemistry : 



