FERMENTED MILK 499 



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 de- 

 stroy 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 temperature 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 stoppered bottles at the same temperature 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 twenty-four hours; if held longer than 

 this, it is advisable to keep it on ice to check the fermentation. 

 The temperature at which the milk is fermented is important 

 in controlling the relative amounts of alcohol and lactic acid. 

 At higher temperatures 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 dis- 

 carded and new kefir made by adding one part of the fermented 

 milk to three or four of fresh milk. In order to remove the 

 grains the kefir should be strained through cheese-cloth, and 

 #fter thorough washing to remove the curd the grains may be 

 dried by exposure to the sun on pieces of blotting paper. In 

 this condition they are said to retain their vitality for several 



