SKIMMING EFFICIENCY OF THE SEPARATOR 97 



The relative effect of different temperatures of the milk 

 at the time of separation on the per cent of fat left in the skim 

 milk from various makes of hand separators is shown in 

 table 8. 



Similar results were obtained by Eckles and Wayman 1 and 

 by Guthrie. 2 



At a temperature below 70 degrees F. most separators 

 began to clog, due to the excessive viscosity and the tendency 

 of the milk and cream to churn. 



Control of Temperature of milk. On the farm the simplest 

 way to have the milk at the right temperature for separation, 

 is to separate immediately after each milking. This practice 

 does away with the bother of artificially heating of the milk 

 before separating, for which the average farm is not properly 

 equipped and which would be necessary, especially in winter, 

 if the milk were held over for separation from the previous 

 milking or previous day. 



In the factory, however, where the milk arrives already 

 cooled, special provision is required to heat the milk to the 

 proper temperature (95 to 100 degrees F.) before it passes into 

 the separator. This is most easily accomplished by the use 

 of a continuous milk heater similar to a flash pasteurizer. In 

 some creameries which receive whole milk, the milk is heated 

 to pasteurizing temperature preparatory to separation. This 

 has the advantage of pasteurizing not only the cream but also 

 the skim milk. From the stand point of skimming efficiency, 

 however, nothing is gained by this practice. The fat lost in 

 the skim milk by separating the milk at temperatures of 145 

 to 185 degrees F. is practically equal to that lost when sepa- 

 rating at 95 to 100 degrees F. Experience has further shown 

 that the separator is more prone to clog with milk at pasteuriz- 

 ing temperature and has to be taken apart oftener for cleans- 

 ing. This hot milk deposits more separator slime. Additional 

 disadvantages of pasteurizing the milk before separation, in- 

 stead of pasteurizing the cream are, the greater cost of the 

 pasteurizing equipment and the greater expense of heating. 



1 Eckles & Wayman. Factors Affecting the Per Cent of Fat in Cream 

 from Farm Separators. Missouri Bulletin No. 94, 1911. 



2 Guthrie. Variations in the Tests for Fat in Cream and in Skimmed 

 Milk. Cornell Bulletin No. 360, 1915. 



