362 CHEESE 



Van Slyke and Hart found in Cheddar cheese 

 twenty-four hours old that only about 6 per cent, of 

 the total nitrogen in it was soluble in water, whereas 

 in a ripened one, nine months old, 53 per cent, was 

 soluble. The changes in the proteins during the 

 ripening of cheese resemble those observed in peptic 

 or tryptic digestion of proteins, and, as far as they go, 

 are similar to a process of putrefaction, proteoses, pep- 

 tones, and amino-acids being produced in both cases. 

 In ordinary putrefaction, however, certain compounds 

 are produced, especially oxyacids, phenol, indole, skatole, 

 and various gaseous substances which are never met 

 with in normally ripened cheese. Possibly the milk- 

 sugar, or the organic phosphorus compounds have an 

 inhibiting effect on the putrefactive bacteria, or the 

 organisms which utilize carbohydrates check or destroy 

 them. 



The changes in the constituents of cheese, which 

 have just been described, take place slowly, and almost 

 uniformly, throughout the whole mass of hard pressed 

 varieties, such as Cheddar, Emmenthal, and Edam, the 

 time taken to obtain a thoroughly ripe condition being 

 several months. Most of the whey is removed from the 

 curd at the time of manufacture of this type of cheese. 

 On the other hand, in the soft cheeses a much greater 

 amount of whey remains in the curd, and ripening takes 

 place at a rapid rate, the casein being broken down into 

 soluble compounds in a few days. Ripening begins on 

 the outside and proceeds inwards, a section of a partially 

 ripened specimen showing a distinct outer layer of soft, 

 ripened, creamy material, surrounding an interior of firm, 

 white, unaltered curd. 



(ii) Aroma and flavour. During the ripening process 



