DAIRYING 17 



favorable for cream rising than is that of the rooms in which the 

 shallow pans of milk are usually set and the milk does not sour 



so quickly. 



242. The sudden chilling which warm milk receives by sub- 

 merging the cans in cold water is beneficial for gravity cream 

 separation because it retards the grouping of the fat globules into 

 clusters, as already described. When a temperature of near 40 

 degrees F. is maintained for 12 to 24 hours the cream separation 

 is nearly complete if all the conditions are favorable. 



243. (1) The "Cooley process" is a good illustration of the 

 "deep setting" method of creaming milk. After milk is set in the 

 "Cooley" cans, the cream is obtained by drawing off the milk 

 from the bottom of each can through a faucet, which is so made 

 that the flow of skim milk will stop when the cream is reached. 

 A strip of glass placed in the side of the can enables the operator 

 to see the thickness of the cream and to adjust the faucet ac- 

 cordingly. 



244. When the skimming faucet at the bottom of the can is 

 once opened the flow of skim milk should not be checked until 

 the cream is reached, as repeated opening and closing of the faucet 

 sets up currents in the milk, which again mixes the cream already 

 separated. This practice not anly makes the cream thin, but it 

 allows too much of the cream to pass away with the skim milk 

 and diminishes the efficiency of the skimming. The skimming 

 faucet is usually set so that the flow of milk will stop at about 

 one to two inches below the cream line. If drawn close to the 

 cream line there will be too much loss of fat in the skim milk. 



245. The "deep setting" cream may be skimmed every 12 

 hours or just before the next milking, so that the same cans may 

 be in constant use. The thinness of the cream is due somewhat to 

 this short time of setting and is also influenced by the carefulness 

 with which the skim milk is drawn off. 



This "Cooley" cream usually contains from 15 to 20 per cent. 

 fat and the skim milk may test as low as 0.2% fat, but the average 

 test of the skim milk from deep setting is about .75% fat. This 

 is 0.25% fat less than the average skimming done with shallow 

 setting so that on the whole the "deep setting" of milk for cream 



