CHEESE 93 



then set with rennet. Three ounces of a standard ren- 

 net extract to 1,000 lbs. of milk is usually sufficient. 

 Enough should be used so that the milk will show be- 

 ginning coagulation in 10 to 15 minutes and be ready to 

 cut in 30 to 40 minutes. 



The extract should be diluted with ten times as much 

 water and is then poured into the milk under vigorous 

 stirring so as to be thoroughly distributed and incor- 

 porated in the whole mass. 



Owing to the scarcity of the raw material for rennet 

 extract during the war, pepsin extracted from hogs' 

 stomachs has been substituted in many factories and is 

 used either in dry form or as a liquid extract instead 

 of rennet extract. 



With pepsin as the coagulant it is necessary to ripen 

 the milk somewhat further than if rennet is used, in 

 fact to the danger-point where a little more acidity is 

 apt to do harm and produce a dry and crumbly cheese 



either blown up and dried in the air protected from sunlight and rain, 

 or spht lengthwise and spread out flat and salted on both sides. 



In the laboratory the ferment is extracted by chemicals and a pure, 

 clear liquid extract is prepared, of uniform strength and good keeping 

 quahty. Or the extract is condensed into a powder which again is 

 compressed into tablets of great strength. 



The ferment acts best when the milk is lukewarm, but it will do the 

 work at temperatures ranging from 50°, or even lower, to 120° F. 

 Strongly pasteurized or sterilized milk will not curdle with rennet, 

 but milk pasteurized at a low temperature is not changed enough to 

 prevent it from making a firm curd. More rennet does not make a 

 finner curd but causes the milk to curdle quicker; less rennet makes 

 the process slower. Diluted milk will not curdle firmly, and the failure 

 of milk to make a smooth coagulum of the usual consistency and in 

 the usual time, the temperature being right and the regular amount 

 of a standard rennet being u.sed, is a never-failing proof that something 

 is the matter with the milk. It has been changed from its natural con- 

 dition by over-heating in pasteurization or by watering or doctoring, 

 or it h^s not been properly ripened. 



