^ / 

 ' If* 



264 AGRICULTURAL BACTERIOLOGY. 



is the cause of the ripening of any one of the types of hard 

 cheeses. The difficulty lies chiefly in the fact that the process 



is such a long one and that so many different 

 FIG. 32. species of bacteria are found in the cheese at 



different times. This makes it impossible to 



say which are essential and which incidental. 



(Fig. 32.) 



ABNORMAL RIPENING. 



Brief mention must now be made of types of 

 \ 

 v \ \ r^=- cheese-ripening which are undesirable. Our 



Bacteria iso- knowledge of abnormal ripening is, in some re- 

 lated from cheese spects g reate r than our knowledge of the normal 



and supposed to r 



contribute to its processes. It is sometimes said that half of the 

 "HM".*) cheese made fails to be properly ripened. Some 



of the abnormal cheeses are only slightly " off" 

 in flavor and will sell in market as passable cheeses. " Off 

 flavors " in cheese are numerous and varied. Our taste has 

 set a certain standard as the type of flavor which we want in 

 cheese, and the cheese coming closest to it is regarded as the 

 best. But the flavors that develop in the ripening are of all 

 sorts and strengths. Some come close to the standard, others 

 fall very slightly short, others have a slight taste which is 

 foreign, and these pass by imperceptible grades into those whose 

 flavor is so inferior as to render them useless. It is impossible 

 to classify all these types of " off" cheeses. Even the cheese- 

 maker cannot do so, although he recognizes many varieties. 

 To reduce the proportion of these inferior cheeses is, of course, 

 the desire of the cheese-maker, and it is for this purpose that 

 bacteriologists are trying to discover some better means of 

 regulating the ripening. 



There are some types of abnormal cheese-ripening which 

 are more pronounced and more easily described, and of these 

 some of the most serious are due to microorganisms. The 



