CHAPTER II 

 THE CHEMICAL COMPOSITION OF MILK 



THE chemical composition of milk is very complex, being 

 composed of the following constituents or groups of substances : 

 (1) Water; (2) fats; (3) nitrogen compounds (casein and 

 albumin) ; (4) milk-sugar ; (5) mineral constituents or ash. 



A few other substances occur in small quantities and will be 

 discussed later, but they are present in such small amounts 

 that they are not considered of much practical importance in 

 the handling of milk or its products. The constituents of milk 

 less the water are frequently grouped together as the milk 

 solids or total solids, and the total solids without the fat are 

 known as the solids not fat. The watery solution of all the 

 solids except the fat is termed the milk serum. It is a viscous 

 liquid with a whitish color. 



The ingredients in milk vary more or less widely in percent- 

 age, being influenced by a number of factors or conditions. 

 Therefore, no absolute figures can be given as representing the 

 average composition, since any average which might be obtained 

 will depend on the analyses of the individual samples from which 

 each average is made. The best idea can be obtained from 

 results by various workers, such as those given below represent- 

 ing averages from large numbers of individual analyses. 



Richmond gives the average chemical composition of cow's 

 milk in England as shown by about 280,000 analyses covering 

 a period of seventeen years as follows : 



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