CHEESE MAKING. 151 



plays a similar part in tie ordinary process of digestion 

 in the calfs stomach. Kennet solidifies the milk by 

 separating the casein from solution ; the fat globules are 

 separated at the same time, being entangled in the curd 

 formed. The action of rennet is very slow in the case 

 of cold milk; it acts most speedily at a temperature of 

 98 Fahr. ; above this point the action rapidly declines, 

 and ceases at about 130 Fahr. Milk becomes slightly 

 sour when curdled by rennet, but the production of acid 

 (lactic acid) is not essential to the curdling. 



The composition of cheese depends greatly on that of 

 the milk from which it is made ; rich cheese is made 

 from new milk, cream being sometimes added to the 

 milk for the production of the richest sorts ; poorer kinds 

 of cheese are made from milk wholly or partially 

 skimmed. 



The temperature at which the milk is curdled is of 

 great importance. If the temperature is low the curd is 

 very tender, and the whey difficult to separate ; if, on the 

 other hand, the heat is too great, the curd shrinks too 

 much, and becomes hard and dry. Temperatures from 

 75 90 are employed for different kinds of cheese, but 

 80 86 is the temperature most commonly chosen. 



When the curd is sufficiently firm it is carefully cut in 

 all directions, and the whey allowed to drain off. The 

 curd is often scalded with hot whey after cutting, with 

 the view of making it shrink and harden : the temperature 

 used at this point must not exceed 100 Fahr. The 

 drained and broken curd is next put into a press, to 

 remove more effectually the last portions of whey. It is 

 then pulverised in a mill, salted, again passed through 

 the mill, and is then ready for filling into the frames. 



