CREAM RIPENING. 



195 



The optimum temperature, or the temperature at which they 

 grow best is, according to Russell, from 90° to 95° F. At this 

 temperature the germs which cause undesirable results also grow 

 most rapidly in cream. Cream contains germs both of the 

 desiarble and the undesirable type. At a comparatively low 

 temperature (between 60° and 70° F.) the greatest relative 

 growth of the desirable germs is produced. Bacteriologists also 



Fig. 128. — Cream-ripening room in the Model Creamery at the 

 World's Exposition, St. Louis, Mo. 



tell us that the casein ferments as a rule thrive better at a 

 lower temperature than do the lactic-acid ferments at the same 

 temperature. This, keeping in mind that better results are 

 obtained by ripening at lower temperatures (60° to 70° F.), 

 seems to indicate that the flavoring substances are not formed 

 entirely by the action of certain germs producing lactic acid, 

 but that the flavoring substances are probably due to the 

 joint action of several species. Lactic acid itself does not have 



