j644 The Cornell Reading-Courses 



hours, and the fat, being lighter than the rest of the milk, rises to the top; 

 the cream is then skimmed off, or the skimmed milk is removed through 

 a faucet in the bottom of the tank in which the milk is contained. In 

 the second method the cream is extracted in a separator by means of 

 centrifugal force. The milk is allowed to flow into the rapidly revolving 

 bowl of the separator, and the fat, being lighter than the rest of the milk, 

 is forced toward the center of the bowl. As the revolving bowl becomes 

 filled with milk the cream is forced out through the proper channel. 



The statement has been made that separator cream is not so easily 

 digested as is cream raised by gravity. The reason given for this is that 

 the emulsion of fat is broken up by the separator. The truth of this 

 statement has never been proved, and it is quite likely that separator 

 cream is just as easily digested as is cream obtained by the gravity process. 



SKIMMED MILK 



Skimmed milk, or milk serum, is milk from which the fat has 

 been removed. No process of separation is entirely complete and 

 so a small percentage of fat remains in the skimmed milk. In skimmed 

 milk from the separator the percentage of fat is very small, the aim of 

 creamerymen being to get an average of not over .04 to .05 per cent. 

 Small hand separators do not usually skim so closely as do large factory 

 separators, but any separator should skim below .1 per cent fat. 



The following table shows the percentage composition of skimmed 



milk from the separator: 



Percentage 



Water go . 60 



Fat .10 



Sugar 4-95 



Casein 3 • ! 5 



Albumen .42 



Ash .78 



The food value of skimmed milk is not always appreciated. By referring 

 to the above table it will be seen that skimmed milk is rich in protcids 

 (casein and albumen), which makes it a valuable food, especially for grow- 

 ing animals. 



BUTTERMILK 



Buttermilk is the material left after churning butter from cream. Its 

 content depends somewhat on the percentage of fat lost during the 

 process of churning, and frequently it is diluted with the water in which 

 the butter is washed. 



