336 MILK AND MILK PRODUCTS. XIV. 



% 

 Sugar ... ... 4-0 to 5-0 



Proteids ... ... 3-3 to 4-0 



Ash ... ... ... 0-7 to 0-8 



The losses of fat in butter-making occur in the skimmed 

 milk, in the butter-milk, and in mechanical loss of butter. In 

 American stations the loss varied from 7 to 25 %. When the 

 separator was not used the loss was greatest with Ayrshire 

 and Holstein cows and least with Guernseys and Jerseys. 



Cheese is formed from milk by coagulating the casein, which 

 entangles and carries down with it the greater portion of the 

 fat, while the sugar, albumen, and a portion of the casein 

 remain in the whey. 



The coagulation of the casein may be brought about, as 

 already described, either by acids or, more usually and with a 

 better product, by rennet. The curd after separation from the 

 whey is pressed and allowed to "ripen," a process somewhat 

 obscure, but probably dependent upon micro-organisms. 



The composition of both curd and whey will naturally vary 

 with that of the milk from which they are formed, whether 

 this be whole milk, skim-milk, or enriched by the addition of 

 cream. 



The curd and whey from whole milk have the following 

 average composition : 



C'iml %. Whey %. 



Water ... ... 50'0 92-94 



Fat ... ... 26-7 0-35 



Sugar ... ... 2-3 5-10 



Casein ... ... 2OO 0-46 



Albumin... ... trace 0'46 



Ash 1-0 0-69 



100-0 100-00 



The character of the curd produced depends largely upon 

 the temperature at which the rennet is introduced, also upon 

 the acidity of the milk. 



As already stated, rennet acts most rapidly at about 37 (or 



