DAIET CHEMISTRY 



CHAPTER I 

 THE COMPOSITION OF MILK 



1. Complexity of Composition. — When milk is 

 separated into its component parts, as water, fat, 

 casein, albumin, sugar, and ash, the process is called 

 analysis. While these are the principal compounds 

 obtained when milk is analyzed, there are a num- 

 ber of other substances present in smaller amounts 

 which affect the quality of milk both for manufac- 

 turing and food purposes. Milk is one of the vital 

 fluids of the animal body and is necessarily of com- 

 plex composition. 



2. Milk Serum. — Of the various constituents of 

 milk, the sugar, ash, and albumin are in solution, 

 and in the fresh milk the casein is practically in a 

 soluble form. The fat, however, is not in solution, 

 but is in the form of minute globules suspended in 

 the solution which contains the sugar, ash, albumin, 

 and casein and which is known as the milk serum. 

 The milk serum includes all of the constituents of 

 the milk except the fat. The term "serum solids" 

 is applied to those substances of milk which are dis- 

 solved in the water, — the sugar, ash, albumin, and 

 casein taken collectively. 



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