12 



&o carefully Postered by the cheese-maker, is to create the requisite acidity in 

 order that the pepsin of the rennet may exercise its digestive action on the 

 cheese; and it appears certain that the fundamental curing changes commence 

 during the maturing of the curd in the vat, but do not make themselves manifest 

 til] later. 



Pkoouction of Flavor. 



Production of Flavor. The most important characteristic of cheese is its 

 flavor. Buyers of cheddar cheese, especially, judge very largely by the flavor; 

 and no other characteristic counts for so much in estimating the market value. 

 It is, therefore, necessary that the factors which contribute to the production of 

 flavor should be thoroughly understood. 



B. coli, B. lactis aerogenes, Proteus, etc., are sometimes present in milk 

 and cheese, and are to be guarded against, on account of the abnormal flavors 

 which they produce; and other species are occasionally found, but in such small 

 numbers that they produce little or no efifect upon the flavor of the cheese; 

 but from the analyses here presented, it is evident that the lactic acid bacillus 

 is the only species of organism which is of much importance to cheese-makers. 

 Generally speaking, the flavor of the cheese depends mainly upon this organ- 

 ism, when it is present in large numbers, and in what we ordinarily term pure 

 culture, we get the best flavor. It is only when the cheese breaks down under 

 the influence of the enzymes in the rennet, after the ground has been prepared 

 by the lactic acid bacteria, that flavor develops. The rapidity and character of 

 the ripening process, involving the life of the lactic acid bacteria, largely depend 

 upon the temperature at which the cheese is kept; and the most important 

 factor m the control of temperature is a well-regulated cold or cool room. 



The quality of the cheese in the Guelph experiments was in the order of 

 placing in cold storage as regards time— that put in directly from the hoops 

 being the best. In the Kingston experiments, the cheese in the regulated room 

 was superior to that in the ordinary non-regulated room; and in all these best 

 cheese, the most noticeable fact was the high number of lactic acid bacteria 

 which they contained and the length of time these organisms remained alive 

 in them. 



The similarity of germ content in the same kind of cheese, though made 

 in various localities, has a bearing on the question; and we have found that in 

 normal cheese from various parts of the Province, the lactic acid bacillus is the 

 only species that is constantly found in large numbers. 



Conclusions. 



1. The presence of certain undesirable bacteria sometimes produces "oflf" 

 flavors in cheese. The Proteus form found in the cheese of July 29th was likely 

 the cause of the cheese of that date being abnormal in flavor. 



2. In nearly all the cheese examined, gas-producing, digesting or indifferent 

 species of bacteria were found; but they always were in insignificant numbers 

 and soon died out. 



