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, but 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 roquefonii, the 
mold ripening Roque- 
fort cheese (Thorn). 
