EYES AND FLAVOR IN EMMENTAL CHEESE 381 



able to demonstrate that these bacteria occur in numbers from 

 10,000 to 200,000 per gram of cheese. 



Troih-Petersson (1909) using the same methods found approxi- 

 mately the same numbers of lactate-fermenting bacteria as did 

 Von Freudenrich and Orla- Jensen. In a previous report from 

 these laboratories, Eldredge and Rogers (1914), who worked with 

 American cheese of the Emmental type, found this type of organ- 

 ism present in somewhat smaller numbers than was reported by 

 the European workers, and in fact apparently entirely lacking in 

 some cheese. 



Modification of the lactate broth of Von Freudenrich and Orla-Jensen 



For the growth and isolation of lactate-fermenting bacteria 

 from Emmental cheese. Von Freudenrich and Orla-Jensen (1906) 

 used a calcium lactate broth of the following composition: 



per cent 



Pepton (Witte) 2.0 



Sodium chloride 0.5 



Dipotassium phosphate 0.2 



Calcium lactate 2.0 



Although such a mixture is obviously faulty, due to the incom- 

 patibility of the calcium and phosphate ingredients, resulting in a 

 heavy precipitate of an uisoluble calcium phosphate upon steriliza- 

 tion, the broth as used by Von Freudenrich and Orla-Jensen, so far 

 as we are aware, has not been modified by subsequent workers who 

 have used it extensively for studies of the propionic and butyric 

 acid-forming groups of bacteria. Only recently Boekhout and 

 De Vries (1917) have employed it in an extensive study of the 

 bacteria responsible for gas formation in cheese. 



It need hardly be mentioned, assuming that the several com- 

 ponents of the broth are in fact of value, that the ingredients 

 added should not be rendered inert by precipitation. This may 

 be obviated by the use of another salt of lactic acid, such as sodium 

 lactate, in place of the calcium. The commercial sodium lactate 

 syrup may be used if desired, but we have found it convenient 

 to prepare the sodium lactate just before use by neutraUzing the 

 desired amount of lactic acid with sodium hydroxide. The 

 sodium lactate broth has been found to be in all respects as good 



