238 BACTERIA IN CHEESE MAKING. 



cheese. In short, the development of flavors in hard 

 cheeses is as yet an unsolved problem. They are probably 

 not due to the action of the enzyme, and must therefore be 

 attributed to the action of microorganisms ; but what kind of 

 microorganisms produce ,them, and under what conditions 

 they may be most satisfactorily developed are problems that 

 bacteriologists have not settled, and upon which they are now 

 assiduously working. 



FIG. 34. 

 ^ / 



FIG. 33. m ^jf f 



f\ ^^ / \Jl/ 



Bacteria isolated from cheese and 



Bacteria producing cheese flavors. (Conn.) supposed to contribute to its ripen- 



ing*. ( H^eigmcinn*) 



The ripening of cheeses thus appears to be an extremely 

 complicated phenomenon. It is due to the formation of new 

 chemical products, formed partly by enzymes and partly by 

 microorganisms. Two enzymes are concerned, pepsin and 

 galactase, and many kinds of microorganisms. Sometimes 

 molds and sometimes bacteria are the most significant. The 

 soft cheeses are ripened more by molds and miscellaneous 

 bacteria, while the hard cheeses more under the influence of 

 lactic bacteria. 



Ripening at Low Temperatures. Reference must be made 

 to the ripening of cheeses at low temperatures which has 

 been recently discussed. Babcock and Russell (248) have 

 shown that American Cheddar cheeses may be ripened at 

 temperatures only a few degrees above freezing, and this 

 observation has been confirmed by others. The ripening, 

 under these conditions, takes a much longer time than at 



