i_>6 



Transactions of the Canadian Institute. 



[Vol. VII. 



ACID IN CHEESE.* 



Method. — Five grams of cheese and an equal amount of glass were 

 ground together in a mortar ; lOO c.c. of water was then added and well 

 mixed with the cheese. After standing fifteen minutes, the mixture 

 was filtered through a dry filter paper, and 25 c.c. of the clear filtrate 

 taken for the determination of the acidity. Phenolphtalein was used as 

 indicator. 



Where the acidity was determined in an unfiltered portion, as much 

 as two per cent, of acid was found in the older cheese, probably due to 

 the casein neutralizing the alkali. 



Curd at Milling' showed .54 per cent, acid fig-ured as lactic acid. 



" Salting- " .76 " " 



Cheese 6 days old from Salting- showed 86 per cent. acid. 



6 

 '3 

 13 

 20 

 20 

 27 

 -7 

 34 

 34 

 4' 

 4' 

 48 

 48 



■65 

 225 



.86 

 .81 



•79 

 .86 

 • QO 

 .90 

 .86 



•93 

 1 .02 

 1.08 

 1.08 

 i.oS 

 I .08 

 1.08 

 1.08 

 1.08 



The work of Russell and Wenizirl on the normal cheese flora of 

 Wisconsin cheese, during the entire history of the cheese from the 

 time it was made until it was consumed, has been duplicated in m)' 

 laboratory, but with these differences : 



1. Canadian Cheddar cheese was the subject of study. 



2. The culture medium used was somewhat different ; yeast-water, 

 lactose gelatine, whey peptone gelatine, and ordinary beef broth lactose 

 gelatine were employed. From six to ten Petri dishes were poured for 

 each analysis. 



•These determinations were made by R . Harcourt, Associate Professor of Chemistry, Ontario Agri- 

 cultural College. 



