CHAPTER IX 



THE CHEMISTRY AND TESTING OF MILK AND CREAM 



Milk. 



MILK is a secretion from the mammary gland of the 

 female mammal. It is composed of water, fat, 

 casein, albumin, and ash. The condition in which 

 these parts are present varies. The water is 

 present in its usual form. The fat is held in sus- 

 pension in the form of tiny globules which are 

 invisible to the naked eye and require a powerful 

 microscope to see them. The casein is held partly 

 in suspension and partly in solution. The albumin 

 is present in solution. The sugar is present in 

 solution; while the ash or mineral portion is held 

 partly in solution and partly in suspension. 



If a small quantity of milk be heated until all 

 the water is driven off, that is to say, if milk be 

 heated to 212 F. (boiling point) until no further 

 loss in weight occurs, the part that is left being solid 

 is known as milk solids. As this includes every- 

 thing in the milk except the water, we call it total 

 milk solids ; but as in a large part of dairy work 

 we deal with the milk fat alone, we come to speak 

 of total milk solids in terms of "Fat" and "Solids 

 not fat." 



e r r 



Solids not fat 



1 



1 1 = Total milk solids. 

 t ) 



