SOFT CHEESES. 
205 
The ripening occupies from five to eight weeks, and a series of 
changes takes place in the cheese, of which the following is a 
summary: 
The first phenomenon that occurs is the souring of the curd, 
which is brought about by the Bact. lactic acid type of organism. 
These bacteria grow in the milk previous to the addition of the 
rennet, although the milk is not allowed to become very sour before 
curdling. But they continue to grow during the curdling and for a 
day or two after the cheese is made. If by 
any chance the lactic bacteria fail to develop 
vigorously, a ruined cheese is sure to result. 
The second step in the ripening is the ap- 
pearance on the surface of the cheese of a 
species of mold, which has been named 
Penicillium camemberti (Fig. 44). This mold 
appears in from two to four days and is at first 
of a pure white color; later, when it begins to 
produce spores, it becomes a steel gray, but 
never a deep blue like the common mold. It 
is a species of mold that apparently does not 
occur in America, but is very common in 
Europe in those sections where Camembert 
cheese is made. Its absence from America is 
the chief reason why this country has been unable to make 
Camembert cheese. Where successful cheese of this type has been 
produced, it has been by importing and inoculating this type of 
mold into the American cheese factories. This white mold grows on 
the surface of the cheese, but does not penetrate below the surface. 
After about two weeks it reaches its limit of growth, forms spores, 
and dries down to a somewhat thin crust. The growth of this mold, 
together with other organisms, neutralizes the acid of the curd at 
the surface of the cheese and renders it slightly alkaline. 
In the meantime the mold has secreted an enzyme which has 
the power of digesting the curd. As fast as the acidity of the curd 
is reduced and the enzyme secreted, the latter acts upon the curd, 
changing it from a hard consistency to a soft texture. At first the 
FIG. 44. Penicillium 
camembertii, the mold 
ripening camembert 
cheese (Thorn). 
