TESTING MILK AND CREAM FOR ACID 



593 



The removal of 125 Ibs. of skim milk necessitates the separa- 

 tion of 88.33 : 100= 125 :X, or 141.5 pounds of the 1000 Ibs. of 

 3.5% milk. 



EXAMPLE 8. 



2000 Ibs. of 32 per cent cream are wanted. How many pounds 

 of skim milk starter and how many pounds of 38 per cent cream 

 must be mixed? 



38 32 



32 



6 



38 



38 : 32 = 2000 : X; X = 1684 Ibs. 38% cream 

 38 : 6 = 2000 :X; X= 316 Ibs. starter. 



2000 Ibs. 32% cream. 



In order to secure 2000 Ibs. of 32 per cent cream, 1684 Ibs. of 

 38 per cent cream must be mixed with 316 Ibs. of skim milk starter. 



TESTING MILK, CREAM AND STARTER FOR ACID 



The acidity in milk, cream and starter is intimately related to 

 the flavor and keeping quality of the resulting butter. It is impor- 

 tant for the creamery to know the acidity of the milk when it arrives 

 at the factory so as to determine its fitness for manufacture. In 

 the ripening of cream and starter the acidity expresses the degree of 

 ripeness, and in the neutralization of sour cream the acidity must 

 be accurately determined in order to enable the operator to use the 

 correct amount of neutralizer that will reduce the acidity to the 

 desired point. It is important, therefore, that the creamery use sys- 

 tematically a simple, practical and accurate test of milk, cream and 

 starter for acid. 



Principle of Acid Tests. Numerous acid tests have been 

 devised for this purpose, all of which are based on the principle of 

 measuring the per cent acid by the amount of alkali needed to reduce 

 a measured volume of the sample to be tested to the neutral point. 

 These tests are devised on the basis that -a given volume of a normal 

 solution of an alkali neutralizes the same volume of a normal solu- 

 tion of an acid. By the term "normal solution" is meant a solution 



