206 BACTERIA AND OTHER MICROORGANISMS IN CHEESE. 



cheese is a hard, solid curd from surface to center; but as this enzyme 

 acts beneath the mold there is formed a thin layer of soft material. 

 This layer grows deeper and deeper as it encroaches upon the curd. 

 The enzyme produces a profound change in the casein, converting 

 it first into peptones and similar bodies; later these break down 

 into simpler bodies, or end-products^ among which ammonia may 

 always be detected. These latter end-products give the flavor, 

 and appear to be produced by bacteria rather than by the action of 

 the enzymes secreted by the mold. During the ripening the cheese 

 will be found to have a core of a sour, acid curd in the center, 

 surrounded by a layer of soft, digested material. The cheese ripens 

 thus, from the surface inward, and is not completely ripened until 

 the soft layer reaches the center. 



The flavors are not due to the enzyme diges- 

 tion, T>ut to the end-products of decomposition. 

 In the case of this cheese, as in the hard cheeses, 

 no positive knowledge is at hand as .to the exact 

 source of the flavor. That it is not due to the 

 mold alone is certain, from the fact that the 

 softened cheese may be nearly tasteless, if a pure 

 culture of mold has completed the ripening*. The 

 peculiar Camembert flavor is, beyond doubt, as- 

 sociated with some of the microorganisms grow- 

 ing in or on the cheese, but at present no more 

 is known about the matter. 



Roquefort Cheese. This represents a type of 

 cheese that, like Camembert, is ripened by both 

 bacteria and molds. Closely allied to it are the 

 Stilton and Gorgonzola cheeses. The mold is a 

 blue instead of a white one, and it grows through the cheese and not 

 alone on its surface. To bring about the growth in the center of 

 the cheese special means are devised in its manufacture. The 

 cheese-maker begins by cultivating the necessary mold on bread. 

 After the mold on the bread has produced a great quantity of spores, 

 the mass is dried and ground into powder (Fig. 45). After curdling 

 the milk with rennet in the usual way and draining the curd, it 



FIG. 45. Penicil- 

 lium roquefortii, the 

 mold ripening Roque- 

 fort cheese (Thorn). 



