SKIM-MILK. 203 



3. Only after pasteurization and subsequent proper 

 cooling will this skim-milk reach the high degree of com- 

 parative freedom from bacteria possessed by the separator 

 skim-milk. 



In view of these conclusions we cannot but consider 

 the prejudice against separator skim-milk for human food 

 as unfortunate. It is objected that separator skim- milk 

 is so entirely void of all fat that it is not fit for human 

 food. To this it may be answered that : 



1. Equally poor skim-milk may be obtained by the ice 

 method if the milk is left standing for several days. 



2. Rich skim-milk may also, if desired, be obtained by 

 means of the centrifuge. 



3. By mixing new milk or cream with poor skim-milk 

 any quality of rich skim-milk may be obtained. 



The mere fact that the skim-milk is obtained by the 

 gravity methods is no guarantee that it is rich ; it is often 

 its macroscopic impurities which produce the impression 

 of richness (see p. 139). 



