134 Milk and Its Products. 



the requisite amount of acid ; but if only a slight 

 inoculation is present, a higher temperature will be 

 necessary. Ordinarily, there will be more germs 

 present in the atmosphere during the warm months 

 than in the winter, consequently a lower temperature 

 will bring al)out the same degree of acidit}' in a 

 shorter time in summer than in winter. 



The amount of acid necessary. — The amount of 

 acid that it is desirable to have in the cream at 

 the time of churning depends, of course, largely upon 

 the flavors desired by the consumer. It is important 

 that whatever amount is desired should be uniform 

 from day to day. By far the larger proportion of 

 consumers prefer the flavors that are characteristic of 

 ripening till sufficient acid to slightly coagulate the 

 casein is present. Consumers of delicate taste 

 readilj' distinguish between the flavors due to a 

 greater or less amount of acid, and it is highly de- 

 sirable that some means of determining the amount 

 of acid present be available. The butter -maker of 

 trained senses has little difficulty in distinguishing by 

 the somewhat thickened and glistening appearance of 

 his cream, when stirred, the proper condition of the 

 cream for churning. Besides this, there are, fortunately, 

 more exact means for determining the acidity. 



Acid tests. — Dr. A. G. Manns first suggested the 

 use of an alkali of known strength to determine the 

 proper acidity of cream for churning, and devised 

 what is known as Manns' acid test. It simply con- 

 sisted in neutralizing the acid in the cream with a 

 standard alkali, the standard used being that known 



