246 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 may be 

 any 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. (See Appendix A.) 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 reserved each day to prepare ferment for 

 the following day from whole milk; and with care that 

 the vessels in which the ferment is made are kept 

 clean and sweet, a single ferment may be propagated 

 for from ten days to two weeks. As a matter of fact, 

 there is no reason why a ferment may not be propa- 

 gated for an indefinite time. All that is necessary is to 

 keep everything bacteriologically clean and to prevent 

 infection by never allowing any dust or solid particles 

 to fall into the ferment and never to touch it with the 

 hands. Such a ferment will give more uniform results, 



