BUTTER-MAKING 227 



extent separated. The fibrin clots, being heavy, accumulate 

 upon the bowl of the separator and make up a large part of the 

 slime which is found after large quantities of milk have been run 

 through." 



Methods of creaming 



Several methods for separating the cream from the milk are 

 in use. The oldest method is to pour the milk in pans to the 

 depth of 2 to 4 inches and allow it to stand undisturbed for 

 twenty-four to thirty-six hours, at which time the cream can 

 be removed from the surface by means of a shallow skimmer. 

 While newer methods have largely replaced this one, it is still 

 in general use in some sections. The creaming process is never 

 complete by this method and from 0.5 to 1.0 per cent of the 

 cream may be left in the skim-milk. One of the difficulties 

 in this system is that the casein frequently curdles before the 

 fat globules have all risen, thus interfering with complete 

 creaming. To avoid this, what is known as the "deep setting 

 system" was devised. In this system, the milk is placed in 

 cans 8 to 10 inches in diameter and about 20 inches deep; 

 the cans are set in cold water and the milk thus cooled to the 

 temperature of cold well water or ice water. This cooling 

 checks the growth of the bacteria, and prevents the souring 

 and curdling of the milk. According to Babcock, the 

 immediate cooling also prevents the formation of the fibrin 

 clots and threads, making it easier for the fat globules to rise. 

 But this theory is not borne out by Wing, 1 who found that delay 

 in setting did not affect the completeness of creaming. One of 

 the best forms of the deep setting system is the Cooley Creamer 

 in which the cans are completely submerged in ice water. This 

 can is so designed that the skim-milk can be drawn off at the 

 bottom without disturbing the cream. In this way, less fat is 

 lost in the skim-milk than when the cream is removed from the 

 J C. U. Bui. 29, p. 73. 



