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 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. 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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