CHAPTER XVII 

 TESTING 



TESTING in connection with the manufacture of butter 

 consists in the use of the Babcock test for determining 

 the quantity of milk-fat in whole milk, cream, skimmed- 

 milk, butter, and buttermilk; moisture and salt tests 

 for butter; and acidity tests for milk and cream. The 

 most essential test is the determination of milk-fat, for 

 this is the main constituent of butter. Creameries buy 

 milk and cream on the basis of their fat-content. The 

 fat test for butter is not in general use. When employed, 

 the purpose is usually to determine whether the composi- 

 tion of butter is within the requirements of the law. 

 One reason why the Babcock test, which is the simplest 

 one for fat, is not used for testing butter, is that the tech- 

 nique is not as simple as that of the moisture test. Sim- 

 plicity is essential fora layman, such as a creamery operator. 



The holding of samples for any test is important. If 

 they are to be kept for one or two days or for a longer 

 period, they should be put in glass bottles with ground 

 glass stoppers so that interchange of moisture between 

 the samples and the air may not take place. 



217. Important factors in Babcock test. The Bab- 

 cock test for milk-fat consists in : (1) Obtaining a repre- 

 sentative sample; (2) taking the proper amount for a 

 test; (3) the addition of the proper amount of sulfuric 

 acid to destroy the solids not fat ; (4) proper centrifuging 

 to force the heavier substances in the acid solution to the 



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