60 THE BOOK OF CHEESE 



texture of the ripened cheese was entirely different from 

 that desired for this variety under experiment. These 

 curves apply directly to but one cheese process in which 

 a particular combination of acidity, rennet and time is 

 used to obtain a very delicately balanced result. In other 

 varieties it is equally important to obtain exactly the ad- 

 justment of these factors which will bring the desired result. 



80. Acidity of milk when received. If proper care 

 has been taken, milk should be delivered to the factory 

 fresh, clean and without the development of acid. If 

 the milk has not been handled properly, the early stages 

 of souring or some other unfavorable fermentation will 

 have developed. Such milk may develop too much 

 acid, or gas, or any one of several objectionable flavors 

 during the making and ripening of the cheese. Some 

 cheese-makers become very expert in detecting the first 

 traces of objectionable qualities, but most makers are 

 dependent on standardized tests to determine whether 

 milk shall be accepted or rejected, and when accepted to 

 determine the rate at which it may be expected to respond 

 during the cheese-making process. 



Various tests have been devised to determine the 

 amount of acid present in milk. There are two tests 

 commonly used in cheese-factories. One is known as 

 the " acid test " and the other the " rennet test." 



81. The acid test 1 is made by titrating a known 

 amount of milk (Fig. 9) against an alkali solution of 



1 Publow, C. A., An apparatus for measuring acidity in cheese- 

 making and butter-making, Cornell Exp. Sta. Circ. 7, pages 17- 

 20, 1909. 



Hastings, E. G., and A. C. Evans, A comparison of the 

 acid test and the rennet test for determining the condition of 

 milk for the Cheddar type of cheese, U. S. Dept. Agr. Bur. An. 

 Ind. Circ. 210, pages 1-6, 1913. 



