176 Milk and Its Products. 



required for the ripening will be shortened, and more 

 uniform results be obtained if, in addition to the 

 warming, an artificial starter is used. This ma\' be 

 an}" material containing the germs of lactic fermen- 

 tation in active condition. The whey saved from 

 the previous day, or milk naturally or artificially 

 soured, may be used. An extremely convenient 

 form of starter is made by preparing an artificial 

 ferment in the following way: Ten pounds of 

 whole milk are sterilized at 180° F., then cooled to 

 90°, and sufficient commercial dry lactic ferment 

 added to secure coagulation in twenty -four hours. 

 When coagulated this is added to the extent of 10 

 per cent to enough whole milk to make sufficient 

 starter for one day's use. The amount of starter 

 to be added for the purpose of ripening the milk 

 should be from 2 to 5 per cent, varying with the 

 temperature of the air and the amount of ripeness 

 that it is necessary to develop after the milk reaches 

 the factory. Enough of the ferment should be re- 

 served each day to prepare ferment for the following 

 day from w^hole milk; and with care that the ves- 

 sels in w^hich the ferment is made are kept clean 

 and sweet, a single ferment may be propagated for 

 from ten days to two weeks. Such a ferment will 

 give more uniform results, and is less liable to in- 

 troduce taints and bad flavors, than a ferment made 

 from sour whey, and with a little care and atten- 

 tion, the fermentation will go on regularly from day 

 to day. 



Rennet.— The ordinary source of rennet is the 



