250 



Elementary Principles of Agriculture 



are added and maintained at a temperature favorable 

 to the development of proper flavors and texture in the 

 butter. This is preferably between 60 and 70 Fahr. 

 This practice is known as adding a "starter," and is 

 used extensively in commercial butter- 

 making. In the absence of commercial 

 starters, a little sour milk will prove 

 quite satisfactory. 



357. Gravity Creaming. 

 When milk is "set" to allow 

 the cream to rise, it should be 

 kept cool. The cream rises 

 quicker and more completely 

 if kept cool by ice or moist 

 cloths. Gravity creaming 

 leaves from 0.5 to 1.0 per 

 cent of the butter-fat in 



the milk even when the 

 temperature of the milk 

 is kept at 60 Fahr. The 

 rise of the fat globules of 

 milk to form "cream" is 

 due to the fact that fat 

 is lighter than water or 

 the milk serum. 



358. Centrifugal Cream- 

 ing. The cream separator 



is a machine for separating the cream from milk while 

 fresh. It separates cream much better, quicker and 

 with less work than gravity creaming. Good sepa- 

 rators leave only 0.1 to 0.2 per cent of the butter-fat in 

 the milk. The separator also gives a cleaner cream than 

 can be obtained by the usual methods. The effective- 



Fig. 163. A modern cream separator. 



