DOMESTIC ANIMALS 



321 



the opening of a small tube in the center of the revolving vessel, 

 and is carried off in a constant stream to an outside receptacle. 



The centrifugal separator ordinarily should be able to remove 

 about 98 per cent of the butter fat in the form of cream. 



After the cream is separated it is allowed to ripen before being 

 churned, because butter made from fresh cream seems insipid and 

 lacking in flavor. Under a tem- 

 perature of 60 tjiis ripening will 

 take place within twenty-four 

 hours or less time. This change is 

 effected through certain bacteria, 

 Besides these beneficial bacteria 

 there are often present many 

 harmful forms of bacteria in milk 

 when it is not properly cared for. 



In order to check the growth of 

 harmful bacteria, extreme cleanli- 

 ness should be practiced, and the 

 milk should be cooled as rapidly 

 as possible to a temperature of 50 

 or less. Sometimes it is found 

 best to pasteurize the milk. This 

 consists in heating the milk to a 

 temperature of 160 F. for fifteen 

 minutes and then rapidly cooling 

 it to a temperature of 50 F. This 

 destroys many of the bacteria 

 especially those that are harmful. 



After the proper ripening of the cream, it should be churned 

 as soon as possible. The proper temperature of the cream for 

 churning is 50 to 54 F. in the summer and from 54 to 58 F. in 

 the winter. When the butter granules have reached the size of 

 large grains of wheat, the churning should be stopped. Then the 

 butter should be washed, salted, thoroughly worked, molded, and 

 packed for market. 



In judging butter and estimating its excellence the student 

 should consider the following points: flavor, texture, color, the 

 salting, and lastly the molding and packing. If possible, send to 



PRAC. AGRICUL. 21 



Centrifugal separator. 



