8 DAIRY TECHNOLOGY 



grass in summer. Milk is best for direct consumption as 

 soon as possible after it is drawn and cooled. In case 

 of specially fermented milks this does not apply. On 

 standing, milk undergoes fermentation and decomposi- 

 tion. The extent to which these changes occur depends 

 upon the temperature at which milk is kept and upon the 

 number and kinds of germs in the milk. If milk and other 

 dairy products are kept, they should be held at a low tem- 

 perature. Unpalatable and other ' abnormal milk will be 

 mentioned later. 



Digestibility of Milk. - Milk, generally speaking, ranks 

 high as a digestible food; but in this connection it should 

 be stated that the digestibility of cows' milk varies. First, 

 it varies according to the condition of the milk (whether 

 fresh or old, whether adulterated or not), and according 

 to the composition of the milk. Secondly, the digestibility 

 of milk varies according to the power of digestion of differ- 

 ent persons. Thirdly, its digestibility varies according to 

 the amount consumed, and whether it is taken with other 

 foods or not. 



When milk is consumed, it passes first into the stomach, 

 where the acid and pepsin in the gastric juice curdle and 

 dissolve it. When milk is consumed in large quantities 

 at a time, without the addition of any other food, the curd 

 or casein may gather in lumps. In this condition the gas- 

 tric juice digests it with difficulty. Abnormal fermentation 

 may set in and cause sickness before the digestive juices 

 have a chance to bring the normal digestive changes about. 

 This condition is especially common with infants and with 

 adults having a weak digestive system. 



Human milk curdles differently from cows' milk. The 

 former contains less casein than the latter, and the casein 

 is probably combined with the mineral salts in a different 



