CHAPTER XI 

 HEATING MILK PREVIOUS TO SKIMMING 



Reasons for Heating. — Owing to the fact that all separators 

 will skim closer and not clog so easih- when milk is heated, nearh^ 

 all creameries heat or warm the milk pre\dous to skimming. 

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

 man}- undesirable odors or taints escape, ^^'ith an increase of 

 temperature, the viscosit}' of the milk is lessened, due chietl}' 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. 



B\' warming the milk to a high temperature and leaving it for 

 some time, then cooling quickh' 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 \'ery 

 low temperature for at least three hours, and then is quickh- 

 warmed up to the usual skimming temperature, and skimmed, 

 the warming of the milk has comparative!}" little effect in fjringing 

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

 it is possible to skim milk at the same temperature, and }"et 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 pre^-ious 

 to skimming varies according to flifferent investigators. The 

 temperature mostly employed in the past in this countr\-, and 

 perhaps at the present time, is about 90^ F. This comparativeh- 



ur> 



