574 



ANNUAL REPORT OF THE 



Off. Doc. 



CHAPTEK IV. 



CiiBAM. 



If). Composition of Cream. 



Cream is the fluid product, rich in milk-fat, obtained by removing 

 milk-fat from milk in any manner, along with some portions of other 

 milk constiUietits. Cream contains the same constituents as milk, 

 but in very ditferent relative proportions. Cream contains much 

 more fat than does milk, but less of the other constituents. Cream 

 varies greatly in its fat content, ranging all the way up from 10 per 

 cent, or less. Market cream often contains less than 15 per cent, 

 of fat, but good cream for domestic use, at the prices commonly 

 charged, should cootain 20 to 25 per cent, of fat. The amount of 

 fat in cream depends upon a variety of conditions, but chiefly the 

 method employed in removing the cream from the milk. For illus- 

 tration, we give the composition of several different samples of cream 

 in the following table: 



In the separation of cream, the individual fat-globules are not in 

 any way affected; they are simply crowded together in less space 

 than in milk. 



17. Separation of Cream. 



The fat-globules in milk are relatively lighter than the milk-serum, 

 in which they float free in the form of an emulsion. When milk is 

 permitted to remain quiet in a vessel, the fat tends to rise and ac- 

 cumulate at the surface of the liquid, owing to its lighter specific 

 gravity, relative to milk-serum. In thus passing up through the 

 milk, the fat-globules mechanically carry with them some of the 

 milk-serum. Until receot years, cream was all produced by allowing 

 the fat-globules to separate by gravity, but there have come into 

 gradual use machines that are used to separate cream from milk 



