i6 



BULLETIN 319, U. S. DEPARTMENT OF AGRICULTURE. 



Hammarsten (31) shows in the following table the changes brought 

 about in cow's milk by this fermentation : 



Chemical analysis of kefir. 





2 days 

 old. 



4 days 

 old. 



6 days 

 old. 





2.570 

 .425 

 .071 

 3.700 

 3.619 

 .641 

 .665 

 .230 



2.586 

 .405 

 .089 

 2.238 

 3.630 

 .624 

 .832 

 .810 



2.564 





.390 





.120 





1.670 



Fat 



3.626 



Ash 



.630 





.900 





1.100 







It will be observed that the changes were confined almost entirely 

 to the lactose and its by-products. The casein remained unchanged 

 and the increase in the peptones was insignificant. The lactalbumin 

 decreased slightly. The casein of kefir is, according to this chemist, 

 not especially soluble, but may be more easily digestible because of its 

 finely divided condition. The lactose diminished appreciably, and 

 there was a corresponding augmentation of alcohol and lactic acid. 

 A certain part of the lactose is consumed in the formation of carbon 

 dioxid gas not included in this analysis. 



The following directions are given for making kefir when the 

 grains are available: The dry grains are softened by soaking in 

 warm water, which should be changed several times. When the 

 grains rise to the surface and become white and gelatinous they are 

 ready for use. One part of these grains is used to three parts of 

 milk which has been thoroughly heated to destroy the bacteria 

 already present. The bottles in which the milk and grains are placed 

 should not be stoppered but should be protected from the dust by 

 cloths, inverted cups, or plugs of cotton. They are held at a tem- 

 perature at or near 14° to 16° C. (57° to 60° F.), and stirred or 

 shaken frequently. After eight to ten hours the milk is strained 

 through cloth and put into tightly stopped bottles at the same tem- 

 perature as before. The bottles should be shaken every few hours 

 to prevent the formation of lumps of precipitated casein. The kefir 

 is ready for use at the end of 24 hours; if held longer than this it 

 is advisable to keep it on ice to check the fermentation. The tem- 

 perature at which the milk is fermented is important in controlling 

 the relative amounts of alcohol and lactic acid. At higher tempera- 

 tures the percentage of alcohol is increased, while as the temperature 

 is lowered the alcoholic fermentation diminishes and the quantity 

 of lactic acid formed is greater. After the fermentation is once 

 started the grains may be discarded and new kefir made by adding 

 one part of the fermented milk to three or four of fresh milk. In 



