324 MILK AND CREAM TESTING 



Skim milk has more solids not fat, for the acid to digest, thus 

 about 20 c.c. acid are needed for 17.6 c.c. of skim milk. A little 

 greater care should also be taken in mixing the acid with the 

 milk. All other steps are the same as with whole milk. 



Ordinary gravity skim milk usually tests at least 0.1 per cent 

 and frequently 0.50 per cent. The centrifugal cream separator, 

 properly adjusted, will leave in the skim milk a quantity of fat 

 so small as to read 0.02 per cent or less. 



If 100 pounds of milk testing 4 per cent fat is run through 

 a separator there will ordinarily be produced 20 pounds of 20 

 per cent cream. This leaves 80 pounds of skim milk. If this is 

 found to contain 0.03 per cent fat there will remain in the 80 

 pounds only 0.021 pound of fat (80 times 0.0003 equals 0.021). 

 There is at present no excuse for a fat loss represented by 

 even so small amount as 0.05 per cent. 



Testing Buttermilk. — So far as the testing of buttermilk is 

 concerned it is usually very simple, indeed, provided an accurate 

 sample can be taken. The difficulty in getting a sample is experi- 

 enced because the grains of butter are so large that to include one 

 in the sample will manifestly give altogether too high a reading, 

 while to avoid all will yield a fat reading evidently too low. 



If the cream has been properly ripened and has been churned 

 cold there will usually be an invisible fat loss of about 0.05 per 

 cent, though 0.1 per cent is not as uncommon as it should be. It 

 is not always easy to know in advance whether to put the sample 

 into a skim milk bottle or into a whole milk bottle. Xot infre- 

 quently one of each is used in order that one or the other shall 

 be readable. 



Testing Whey. — Whey obtained in the making of cheese con- 

 tains little more than one-half of the solid matter contained in 

 skim milk of the kind which is attacked by the acid. The sugar 

 and the albumen only remain in appreciable amounts. Since 

 the work to be done by the test acid is only about half as great as 

 in the case of whole milk the quantity of acid to be used in testing 

 is only about one-half as great. 



Bottles are on the market made expressly for the testing of 

 whey. They differ from the ordinary whole milk bottle only in 

 having a bulb sufficiently large to contain two charges of whey 



