252 Milk and Its Products 
ciently ripe a starter is then added, and the milk 
allowed to stand at this temperature until a suffi- 
cient amount’ of acid has developed, care being 
taken that it is frequently stirred and no cream 
allowed to rise. 
The rennet should be added in sufficient quan- 
tity to cause the milk to coagulate in from ten to 
fifteen minutes, and to be ready for the knife in 
from thirty to thirty-five minutes. It was formerly 
supposed that the amount of rennet added had an 
effect upon the whole process of manufacture, and 
particularly upon the curing fermentation, but while 
the matter is still unsettled, later researches. go to 
show that the influence of the rennet upon the 
curing is probably very slight. The amount of ren- 
net to be used will also vary with the strength of the 
extract; two to three fiuid ounces of rennet, of or- 
dinary strength, per thousand pounds of milk is 
sufficient. The rennet should be added to the milk 
in such a way that the coagulation will be uniform 
throughout the whole mass. If the rennet is added 
in full strength and at a high temperature, the 
milk will be immediately curdled as soon as the 
particles of rennet come in contact with it, and 
coagulation will begin in part of the mass before 
the rennet can be thoroughly united with the whole 
body of milk. The rennet should be diluted with 
twenty to fifty times its own bulk of cold water. 
The dilution renders the uniform mingling of the 
rennet with the milk easier, and the cold water 
keeps it inactive until it has been warmed up to the 
