324 'MANUAL OF MILK PRODUCTS 



is normally present in the human stomach during the process 

 of digestion in larger proportions than that added to milk in 

 this process of cheese-making. Further, 95 per cent of the 

 added acid passes out of the cheese with the whey during the 

 process of manufacture. On this account no objection can 

 be made on sanitary grounds to the use of this acid in the 

 manner and for the purposes described. 



"Among different lots of cheese, part of which was made 

 with hydrochloric acid and part with calcium chlorid added 

 to portions of the same milk after pasteurization, those made 

 with acid were found to be more uniform in moisture-content 

 and superior both in flavor and texture to those made with 

 calcium chlorid. The losses of fat in the whey are reduced 

 by the use of the acid. Pasteurization and acidulation of milk 

 for cheese-making appear to be complementary processes. 

 Used together, they furnish a means for bringing milk daily 

 into uniform condition both as to" acidity and bacterial content 

 for cheese-making purposes. 



"The acidulation of milk with hydrochloric acid after pas- 

 teurization is accomplished without difficulty or danger of 

 curdling by running a small stream of the acid, of normal con- 

 centration, into the cooled milk as it flows from the continuous 

 pasteurizer into the cheese vat. One lb. of normal-strength 

 acid is sufficient to raise 100 lb. of milk from 0.16 per cent to 

 0.25 per cent acidity (calculated as per cent of lactic acid). 

 The amount of acid needed each day to bring the milk up to 

 0.25 per cent acidity is read from a table or calculated from 

 the weight of the milk and its acidity, determined by the use 

 of Mann's acid test (titration with tenth-normal sodium hy- 

 drate and phenolphthalein) . The preparation of standard- 

 strength acid in carboy lots for this work and the acidulation 

 of milk present no great difficulty to any one who is able to 

 handle Mann's acid test correctly. 



"After the milk is pasteurized and acidulated three-fourths 



