UNIVERSITY 



OF 



Modern Methods of Testing Milk 

 and Milk Products 



CHAPTER I 



Chemistry of Cows' Milk and Milk Products 



THE normal milk of cows contains the following 

 compounds and classes of compounds : 



(1) Water. (4) Milk-sugar. 



(2) Fat. (5) Salts or ash. 



(3) Nitrogen compounds or proteids. (6) Gases. 



WATER 



The water present in milk, however much its pres- 

 ence may be disguised, is the compound of hydrogen 

 and oxygen with which we are everywhere familiar. 

 The water in milk serves the purpose of holding in 

 solution the soluble constituents of the milk, and it 

 also acts as a diluent, better fitting the mixture' for 

 animal nutrition. 



Variation. The amount of water normally con- 

 tained in milk varies, depending upon such conditions 

 as individuality, breed, stage of lactation, age, char- 

 acter of food, amount of water drunk, state of health, 

 etc. In the case of single milkings of individual cows, 

 the water may vary from 82 to 90 per cent, or more. 

 In the case of milk from herds of cows, the water 

 varies less, usually ranging from 86 to 88 per cent. 



