CHEDDAR CHEESE 323 



Cheese from pasteurized milk. 



While the practice of pasteurizing milk for market purposes 

 and of cream for butter-making has become quite general as 

 a means of protecting the consumer against disease organisms, 

 the pasteurizing of milk for cheddar cheese-making has not 

 been general, because of the effect of the heating process on 

 the coagulation of the casein. When milk is heated to the 

 pasteurizing temperature, certain changes take place in the 

 milk salts which prevent the coagulating action of the rennet. 

 This process of making cheddar cheese has been carefully 

 studied at the Dairy Department of the University of Wiscon- 

 sin, 1 and certain modifications of the regular cheddar process 

 have been worked out which are claimed to give cheese of very 

 satisfactory quality. 



These modifications are described by Sammis and Bruhn 

 as follows : 



"The difficulties met with hitherto in making American 

 cheddar cheese from pasteurized milk are : 



"First. That heated milk coagulates poorly with rennet; 

 and 



"Second. The curd when obtained does not expel moisture 

 precisely as a raw-milk curd does, and this effect is more marked 

 the higher the temperature of pasteurization. The quality 

 and behavior of pasteurized-milk curd suggest that it lacks the 

 acid which is normally produced in raw-milk curds by the 

 action of bacteria on milk-sugar. 



"The first of these difficulties, but not the second, can be 

 overcome by adding calcium-chlorid solution to pasteurized 

 milk. This method has been tried experimentally, but is not 

 recommended for use in American cheese factories. Both 

 difficulties, however, are overcome by adding an acid, prefer- 

 ably hydrochloric, to the pasteurized milk. Hydrochloric acid 



1 Wisconsin Research Bulletin No. 27 and Bui. 165. 



