CHAPTER XI 

 HEATING MILK PREVIOUS TO SKIMMING 



Reasons for Heating. Owing to the fact that all separators 

 will skim closer and not clog so easily when milk is heated, nearly 

 all creameries heat or warm the milk previous to skimming. 

 When the milk is thus heated and stirred in a pure atmosphere, 

 many undesirable odors or taints escape. With an increase of 

 temperature, the viscosity of the milk is lessened, due chiefly to 

 the softening and separation of the fat-globules. Such an 

 increased fluidity of the milk lessens the resistant force of the 

 fat-globules when exposed to the centrifugal force of the sepa- 

 rator. The higher the temperature the more fluid the milk 

 becomes, and consequently the more easily the fat can be sep- 

 arated. 



By warming the milk to a high temperature and leaving it for 

 some time, then cooling quickly again to skimming temperature 

 (90 F.) and separating, the skimming efficiency of the separator 

 is increased materially. If the milk has been standing at a very 

 low temperature for at least three hours, and then is quickly 

 warmed up to the usual skimming temperature, and skimmed, 

 the warming of the milk has comparatively little effect in bringing 

 it into a good condition for skimming. It will thus be seen that 

 it is possible to skim milk at the same temperature, and yet get 

 different results, due to previous temperature conditions. Dura- 

 tion of temperature should be considered as well as the tempera- 

 ture itself. 



The temperature to which milk should be heated previous 

 to skimming varies according to different investigators. The 

 temperature mostly employed in the past in this country, and 

 perhaps at the present time, is about 90 F. This comparatively 



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