DAIRYING ii 



229. When cream is skimmed for churning and butter mak- 

 ing, the milk may stand until the souring process has thickened 

 and curdles the skim milk. This often gives the milk some 48 

 hours or even longer to stand. Nothing is gained by this pro- 

 longed standing excepting the advantage of skimming the cream 

 from curdled milk. Cream will not rise on sour milk, but after 

 standing long enough the cream becomes thick and somewhat 

 tough on the surface, and this aids in taking off the cream be- 

 cause there is no danger of setting up currents which may remix 

 the cream when the skimming is done. 



1. Conditions Influencing "Shallow Setting" Cream Separation. 



230. The completeness with which cream is separated by the 

 "shallow setting" process has been found to be influenced by some 

 one or more of the following conditions : 



. The temperature at which the milk is set. 

 The length of time the milk stands. 

 The condition of the milk serum. 

 The period of lactation of the cows. 

 The size of the butter fat globules in the milk. 

 The depth of the milk layer. 



The skill of the person skimming the cream with the shallow 

 cream skimmer. 



231. The effect which these conditions have on the complete- 

 ness of cream separation by this process may be briefly explained 

 here, as they also have more or less influence on other methods of 

 creaming milk. 



First, a temperature of 40 to 50 degrees F. is favorable for 

 cream rising, as the serum, being the better conductor of heat, is 

 cooled more quickly than the fat and consequently the difference 

 in specific gravity is increased and the cream rises quickly. A 

 thermometer should therefore be placed in the room where milk is 

 set for creaming in order to indicate the temperature, and to show 

 what changes may be needed for keeping the milk at the tem- 

 perature best suited for cream rising. 



