CREAMING 



55 



rator out of plumb, (3) dirty oil or dirty bearings, (4) un- 

 stable foundation, or (5) unbalanced bowl. 



C. The best skimming is not possible with any sepa- 

 rator when the temperature falls below 60° F. A tem- 

 perature of 85° to 98° F. is the most satisfactory for 

 ordinary skimming. Under some conditions the cleanest 

 skimming is obtained at tempera- 

 tures above 100° F. The reason 

 milk separates better at the hig:her 

 temperatures is that the viscosity is 

 reduced. 



D. Sudden heating tends to in- 

 crease the loss of fat in skim-milk. 

 The reason for this is that the fat 

 heats more slowly than the milk 

 serum, which diminishes the dififer- 

 ence between their densities. When, 

 for example, milk is suddenly heated 

 from near the freezing temperature 

 to 85° F. by applying live steam, the loss of fat in 

 the skim-milk may be four times as great as it is under 

 favorable conditions. 



E. Unduly crowding a separator increases the loss 

 of fat in the skim milk. On the other hand, a marked 

 underfeeding is apt to lead to the same result. 



F. The higher the acidity of milk the poorer the 

 creaming. With sour milk the loss of fat in the skim 

 milk becomes very great. 



G. Sometimes large numbers of undesirable (slimy) 

 bacteria find entrance into milk and materially inuease 

 its viscosity. This results in very unsatisfactory creaming. 

 Low temperatures also increase the viscosity of milk 

 which accounts for the poor skimming at these tempera- 

 tures. 



Fig. 19.— Cream Separa- 

 tor. 



