500 MANUAL OF MILK PRODUCTS 



years, although many of the yeasts in the outer part of the 

 grain are killed by the desiccation. It may be necessary to 

 break up the grains with the fingers. When in the wet stage 

 they should not be larger than a walnut. 



Kefir grains cannot ordinarily be obtained in this country, 

 but a good imitation of kefir can be made by carrying on simul- 

 taneously in sealed bottles an alcoholic and a lactic fermenta- 

 tion. Better results can be obtained by inducing the alcoholic 

 fermentation in buttermilk. In this way it is possible to avoid 

 much of the trouble from the formation of lumps of curd. If 

 buttermilk is made for this purpose from whole or skimmed 

 milk, careful attention should be given to the time of curdling 

 and the breaking up of the curd. This is essential to a smooth, 

 creamy kefir. Ordinary bread yeast may be used for the alco- 

 holic fermentation, but as this yeast does not ferment lactose 

 it is necessary to add cane-sugar to the milk. 



(1) Obtain buttermilk from a dealer, or prepare it as directed 

 on page 492. 



(2) Prepare the yeast by adding a half teaspoonful of sugar 

 to a 6-ounce or 8-ounce bottle of boiled and cooled water. 

 Add half a yeast cake to this sugar solution and set in a warm 

 place overnight. This will give an active culture of the yeast 

 and obviate the necessity of adding the yeast cake directly to 

 the milk. This yeast culture should be ready at the time the 

 buttermilk is received or, if made at home, at the time it is 

 curdled. 



(3) Add 1 to 1-j- per cent of sugar to the buttermilk. 



On the quantity of sugar added to the buttermilk will de- 

 pend the extent of the alcoholic fermentation. Theoretically 

 about one-half of the sugar fermented may be converted into 

 alcohol; that is, milk to which 1 per cent of cane-sugar has 

 been added may contain after the fermentation one-half of 1 

 per cent of alcohol. The quantity of sugar added should be 

 governed by the amount of carbon dioxid it is desired to have 



