332 THE CHEMISTRY OF DAIRYING 



COMPOSITION OF THE PRODUCTS. 



DISTRIBUTION OF SOLIDS FROM 100 LBS. OF MILK. 



Whey. The composition of whey, like that of the milk 

 and cheese, is, of course, variable. It depends partly upon 

 the method of treatment, and also upon the skill of the -worker. 

 Richmond has found the amount of fat in it to vary from 

 about 0-04 to 1*35 per cent. The proportion of non-fatty 

 solids is more nearly constant, being from 6 to 7 per cent. 

 The degree of acidity is, of course, very variable. 



Rennet. The essential constituent of rennet is the enzyme 

 (p. 83) called " rennin." It is secreted by special glands in 

 the lining of calves' stomachs. Similar, if not identical, 

 enzymes probably occur in the stomachs of all young mammalia. 

 They have been found also in animals belonging to other 

 genera, and even in certain plants. 



The rennet used in cheese-making is prepared from the fourth 

 stomach of a calf. The stomach is carefully washed and hung 

 up to dry in the air for two or three months. It is then cut 



