CHAPTEE III 



The Constituents of Milk 



THE constituents of milk are fat, casein, albumin, 

 lactoglobulin, lactoprotein, milk-sugar, mineral matter, 

 certain gases in solution, as well as minute traces of 

 other bodies. 



Milk -Fat. The fat may be considered as the 

 most important constituent of milk, not only 

 because its commercial value, as well as the com- 

 mercial value of one of its great products, cheese, 

 depend on it, but because it is the chief constituent of 

 the other and still more important milk product, butter. 



The colour and opacity of milk are largely due 

 to the presence of its fat. It exists in the milk in 

 the form of minute globules, known as the fatty or 

 milk globules, so minute as to be quite invisible to 

 the naked eye. They are apparent, however, if we 

 submit a drop of milk to microscopic examination. 

 It will be seen from the accompanying diagram (see 

 Fig. 8) that they differ very considerably in their 



