62 CREAMERY BUTTER MAKING 



separating temperature of 140 to 170 is preferred. 

 Whenever such high temperatures are employed it is 

 necessary to cool the cream immediately after it leaves the 

 separator to a temperature of 70 or lower. 



MIUC HEATERS. 



There are to be found upon the market two general 

 classes of milk heaters: Those which admit the steam 

 directly to the milk called direct heaters, and those in 

 which the steam enters a jacket surrounding the milk 

 known as indirect heaters. 



Direct Heaters. These are practically nothing more 

 than an expansion in the feed pipe in which the steam 

 enters the milk. They are permissible only when first class 

 steam is available and when milk is to be heated through 

 a short range of temperature. But even under these con- 

 ditions indirect heaters are always preferred. 



The two main objections to the direct heaters are : ( i ) 

 the liability of contaminating the milk with impure steam, 

 and (2) the effect of the sudden heating upon the loss of 

 fat in the skimmilk which may be quite considerable when 

 the milk is heated through a long range of temperature. 



It is well known that the exhaustiveness of skimming 

 with any separator is greatly influenced by the manner in 

 which the milk is heated. In general very sudden heating 

 has the effect of diminishing the difference in the specific 

 gravity between the fat and milk serum, consequently 

 rendering the separation of the fat from the milk more 

 difficult. 



In experiments conducted by the author it was found 

 that in many instances where the milk was received in a 

 partly frozen C9ndition and suddenly heated to a separat- 



