CHAPTER X. 



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 skim- 

 ming. By thus heating and stirring the milk in a pure atmo- 

 sphere, 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 separator. The higher the temperature the more fluid 

 the milk becomes, and consequently the easier the fat can be 

 separated. 



By warming the milk to a high temperature and leaving 

 it for some time, and 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 tem- 

 perature, and skimmed, the warming of the milk has com- 

 paratively Uttle 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. Duration of tem- 

 perature should be considered as well as the temperature itself. 



The temperature to which milk should be heated previous 

 to skimming varies according to different investigators. The 

 temperature that has been mostly employed in the past in 



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