170 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. 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 whole milk; and with care that the ves- 
sels in which 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 
Digitized by Microsoft® 
