Bacteria in Cheese. 177 



Influence of rennet on ripening. The addition of in- 

 creased quantities of rennet extract facilitate the breaking 

 down of the casein in cheese. This is due to the fact that 

 such extracts always contain pepsin, the digestive enzym 

 found in the stomach. This enzym exerts a digestive ef- 

 fect on the casein of cheese, producing those decomposi- 

 tion products (albumoses and higher peptones) that charac- 

 terize peptic action. This effect is dependent upon the 

 acidity of the milk, and does not become marked until 

 there is about 0.3 per cent of lactic acid, which is about 

 the amount developed in the cheddar process. The effect 

 of the rennet then is to aid the galactase in the peptoniza- 

 tion of the casein. 1 



Conditions determining: quality. In determining the qual- 

 ity of cheese, several factors are to be taken into considera- 

 tion. First and foremost is the flavor, which determines 

 more than anything else the value of the product. This 

 should be mild and pleasant, although with age the inten- 

 sity of the same generally increases but at no time should 

 it have any bitter, sour, or otherwise undesirable taste or 



FIG. 32. Showing texture of cheese cured at different temperatures. Right 

 hand, 60 F., crumbly texture; left hand, 40 F., waxy texture. 



17 Kept. Wis. Expt. Stat,, 1900, p. 103. 

 13 



