182 Dairy Bacteriology. 



able to form enzyms (similar in their action to tr3 7 psin r 

 galactase, etc.), and these soluble ferments gradually diffuse 

 from the outside through the cheese. 



Most of these peptonizing bacteria are hindered in their 

 growth by the presence of lactic acid, so that in many cases 

 the appearance of the digesting organisms on the surface 

 is delayed until the acidity of the mass is reduced to the 

 proper point by the development of other organisms, prin- 

 cipally molds, which prefer an acid substratum for their 

 growth. 



In Brie cheese a blue coating of mold develops on the 

 surface. In the course of a few weeks, a white felting ap- 

 pears which later changes to red. This slimy coat below 

 the mold layer is made up of diverse species of bacteria and 

 fungi that are able to grow after the acid is reduced by the 

 blue mold. The organisms in the red slimy coat act upon 

 the casein, producing an alkaline reaction that is unfavor- 

 able to the growth of the blue mold. Two sets of organ- 

 isms are, therefore essential in the ripening process, one 

 preparing the soil for the ferment that later produces the 

 requisite ripening changes. As ordinarily carried on, the 

 process is an empirical one, and if the red coat does not de- 

 velop as expected, the maker resorts to all kinds of devices 

 to bring out the desired ferment. The appearance of the 

 right form is dependent, however, upon the proper reaction 

 of the cheese, and if this is not suitable, the wished-for 

 growth will not appear. 



INFLUENCE OF BACTERIA IN ABNORMAL CHEESE PROCESSES. 



The reason why cheese is more subject to abnormal fer- 

 mentation than butter is because its high nitrogen content 

 favors the continued development of bacteria for some time 



