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 fluid 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 



