Chapter VI 



The Ripening Processes of the Different 



Cheeses 



THE methods of preservation, involving the use of preservatives 

 or bactericidal substances, include the use of harmless acids such 

 as acetic or, better, lactic acid. The latter is not added but 

 produced by allowing the material to be preserved to set up a 

 lactic acid fermentation. This method is applied to the preserva- 

 tion of beet slices, white cabbage (sauerkraut) and other sugar 

 containing fodders and foodstuffs which contain too much water 

 to be dried without the aid of artificial heat. In such cases it is 

 only necessary to exclude air as completely as possible so that the 

 acid-consuming moulds are kept down. The same process may 

 also be applied to milk. If the yeasts and moulds are destroyed 

 by pasteurising in bottles, and the milk is inoculated with a 

 vigorous culture of lactic acid bacteria, it will remain unchanged 

 after the souring process has been completed ; a similar principle 

 is applied in the making of cheese, which is always based on a 

 vigorous development of lactic acid bacteria. Under normal 

 conditions the acid which is produced will always inhibit the 

 growth of other bacteria, and in the closely pressed mass of cheese 

 no moulds will develop, owing to the absence of air. If, as in the 

 case of the hard cheeses, an additional protection is afforded in 

 the shape of a firm cheese rind, all risk of infection is excluded, and 

 a permanent product is obtained. 



The origin of cheese making was without doubt a desire to preserve 

 the valuable constituents of milk in a permanent and easily market- 

 able form. The primitive process, therefore, only involved the 

 drying and salting of the curd, a process which is still employed 

 in several places in the East. Subsequently it was discovered 

 that the curd would also keep without drying, and that with 

 suitable treatment it would acquire other valuable properties into 

 the bargain. The art of cheese making thus became not only one 

 of mere conservation, but also the production of a palatable food, 

 and in the case of the soft cheeses it may well be said that attention 

 has been concentrated on the latter point. 



The curd is separated by the action of either rennet or lactic 

 acid ; we may commence with an examination of the mechanism 

 of the two processes. 



