EYES AND FLAVOR IN EMMENTAL CHEESE 385 



a rather uncertain one for the quantitative estimation of the lac- 

 tate-fermenting bacteria of cheese. It has been noted on several 

 occasions that the distillation for volatile acids gave negative re- 

 sults whereas further propagations from the culture used showed 

 that lactate-fermenting bacteria were present. This phenomenon 

 is probably to be explained by the presence in the culture of other 

 organisms which consume the volatile acids. That this may 

 sometimes be the case was indicated by the results obtained on 

 certain samples of cheese in which volatile acids were produced 

 from the high dilutions of cheese in lactate broth whereas the low 

 dilutions, which contained a much heavier inoculation and a 

 greater variety of organisms, gave negative results. In this work 

 we have checked ourselves quite thoroughly against such errors 

 by running all of our dilution cultures in triplicate, and also by 

 making further examinations and propagations from dilution cul- 

 tures which gave negative results. Thus we have on several 

 occasions demonstrated the presence of the lactate-fermenting 

 bacteria from cultures which gave negative results on the original 

 test. 



II. THE CAUSE OF EYES AND FLAVOR 



In our work on Swiss cheese during the past few years the 

 identity of the organism responsible for the development of the 

 characteristic flavor, as well as the eyes, of Emmental cheese has 

 been quite clearly established. The ability of this organism to 

 play these roles in the ripening of cheese has not only been estab- 

 lished by carefully controlled laboratory experiments, but also 

 under practical commercial conditions in factories located in 

 widely separated areas of the country. 



GENERAL CHARACTERISTICS 



Morphologically the organism is a minute rod about twice as 

 long as it is broad. It makes little or no growth on agar slope 

 cultures; in agar stabs growth takes place throughout the length 

 of the puncture but not on the surface. In agar shake cultures 

 there is likewise no growth on the surface whereas good growth 

 takes place throughout the medium ; as incubation continues over 



