THE RELATION OF MICROORGANISMS TO CHEESE 437 



In three or four days the cheese becomes covered with the growth 

 of Oidium lactis; the characteristic mold of Camembert cheese, Peni- 

 cillium camemberti, appears later, within five to six days. These 

 molds reduce the acidity of the curd, and through the enzymes, which 

 they produce and which gradually diffuse into the cheese, proteolyze the 

 curd very completely. The appearance of the cheese when cut in- 

 dicates the depth to which the enzymes have penetrated; when the 

 entire mass is acted upon, the cheese is ready for use. The reduction of 

 the acidity by the molds exposes the cheese to the attacks of putre- 

 factive bacteria and it soon becomes unfit for use after it is completely 

 ripened. A number of different kinds of bacteria are found in the 

 slimy surface layer, but their r61e is not known. 



The development of the characteristic flavor and aroma is dependent 

 on a certain relation between the various biological agents concerned 

 in the ripening. This balance is dependent on very narrow conditions 

 of temperature and humidity; slight changes in these environmental 

 conditions favor or retard the individual types in varying degrees. If 

 the equilibrium essential for the development of typical flavor is 

 destroyed this cheese fails to ripen properly and is of low value. The 

 manufacture of Camembert cheese is a delicate problem in the ecology 

 of microorganisms, and because of this fact the manufacture is attended 

 with greater difficulties than is the case with most tj^pes of hard cheese. 



