152 MILK [ix 



Chemical Changes Cheese undergoes during 

 the Ripening Process. But what, it may be asked, 

 are the chemical changes which cheese undergoes in 

 the ripening process ? Eipening, from a chemical point 

 of view, may be said to consist chiefly in the trans- 

 formation of the characteristic constituent of cheese, 

 viz. the casein, from the insoluble condition in which 

 it is present in fresh cheese into certain soluble 

 albuminoid bodies. The unpalatable nature of fresh 

 cheese is due to the fact that the casein is in an 

 insoluble condition. By allowing the cheese to 

 ripen, therefore, a certain amount of decomposition 

 of the casein is effected, and the solubility of the 

 cheese in water is consequently largely increased. 

 It is, therefore, to the presence of these soluble 

 bodies that the flavour, quality, and condition of a 

 cheese are largely due. What these decomposition 

 products exactly are is still doubtful. We know, 

 however, that the milk-sugar, which is present to a 

 small extent in fresh cheese, is no longer to be 

 found in ripened cheese. It has been decomposed 

 into such bodies as lactic acid and, it may be, 

 butyric acid. The fat in cheese seems, however, to 

 undergo very little decomposition in the ripening 

 process. Among other decomposition products, alco- 

 hol, oxalic acid, carbonate of ammonium, leucin, and 

 tyrosin have been identified. During ripening, too, 

 there is generally produced a certain amount of 



