56 



MILK 



parts of the milking. The relative size of fat globules in different 

 portions of the milk is illustrated in the following chart (Fig. 18) 

 prepared from figures by Bitting. 



According to this chart the majority of globules in skimmed 

 milk are 6 microns in diameter; in fore-milk, whole milk, and strip- 

 pings, 8 microns; and in middle milk, 12 microns. However, the 

 strippings contain the greatest number of large globules, measur- 



12 16 20 24 



SKIM Mru — 

 350 



300 



250 



200 



ISO 



FORE MILK- 



WHOLE MILK- 

 LAST niLK-- 



NUMBER OF GLOBULE^" 



Of EACH SIZE PER 1000 



MIDDLE MILK 



28- MICRONS 

 450 



en NUMBER OF GLOBULES 

 ''of EACH SIZE PER 1000 



- WHOLE MILK 



'FORE MILK 



LAST MILK 



24 28- -MICRONS 



\ '^MIDDLE MILK 

 •SKIM MILK 



Fig. 18.— The number of globules of each size per 1000 globules. 



mg from 20 to 24 microns in diameter. It is clear that strippings 

 cream more rapidly than fore-milk and that the creaming of whole 

 milk improves when the udder is milked dry. 



7. Centrifugation of milk is used largely for two purposes— 

 the separation of cream, and the removal of foreign substances. 

 The violent motion in the machine breaks up the fat clusters, so 

 that centrifugated milk does not cream as well as untreated milk. 



