CHAPTER XXXI 



DAIRY PRODUCTS 



Surely the churning of milk bringeth forth butter. THE BIBLE 



484. Recent progress. In dairy regions each person con- 

 sumes, on an average, a pint of milk a day. Outside of the dairy 

 regions, only about half this amount, on the average, is con- 

 sumed by each person. Long ago it was discovered how to 

 make cheese and butter from milk, and the same principles 

 were used then as now. Perhaps more progress has been made 

 within the last fifty years, however, in improving the dairy cow 

 and in the sanitary and economical handling of dairy products 

 than in all time before. Increased production has been accom- 

 plished by modern methods of breeding, feeding, and testing 

 the cows. The processes of dairy manufacturing have been pro- 

 foundly influenced by the invention of the centrifugal separator, 

 the discovery of the Babcock test (Fig. 185), and the develop- 

 ment of methods of cold storage, of making condensed milk, 

 and of cheese making. 



485. What milk contains. Secretion of milk takes place in 

 the milk glands or udders of animals which suckle their young. 

 In the process of secretion the composition of the materials 

 taken from the blood is changed by some unknown process to 

 the substances found in milk. Milk is an opaque, yellowish-white 

 fluid and possesses a sweetish taste. One hundred pounds of 

 average milk contains 87.2 pounds of water, 3 pounds of casein, 

 3.9 pounds of butter fat, 4.75 pounds of sugar, .4 pounds of 



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