PART TWO 



THE TESTING OF DAIRY PRODUCTS 



The percentage of butter-fat is made the basis for deter- 

 mining the market value of nearly all dairy products, and is 

 calculated by the Babcock test. In connection with the test 

 for butter-fat there are several other tests which are often 

 used to determine the quality and the composition of dairy 

 products. In acquiring a knowledge in the manipulation of 

 these tests the student will need to practice extreme accuracy. 



Taking Samples. The butter-fat exists in milk in 

 minute globules which float about in the milk and are brought 

 to the top by the action of gravity. The milk and cream 

 must be mixed thoroughly with a stirring rod or by pouring 

 from one container into another before taking the sample to 

 test. A small sample dipper or sampling tube will serve in 

 taking the sample. 



A composite sample is one made up from milk delivered 

 at different times or from several cans, and should give an 

 average test for the period or for the total amount of milk. 

 Care is necessary to take a proportionate amount from each 

 can in order to get a representative test of the whole amount. 



Preserving Samples. In case the samples cannot be 

 tested immediately, they may be kept from souring by using 

 chemicals. The preservatives in common use are corrosive 

 sublimate and bichromate of potash. These are put up in 

 convenient tablet form of sufficient strength that one or two 



