Bacteria in the Cheese Industry. 167 



rendered worthless, but even where the development is 

 not so marked, the flavor of the cheese is impaired and 

 the market value diminished. The difficulty may occur at 

 almost any season of the year, but the trouble is most 

 frequently observed in the late summer months. So 

 common are these difficulties that they may be regarded 

 as the worst cheese troubles with which our cheese- makers 

 have to contend. - 



This same defect occurs in other kinds of cheese, but 

 it is particularly marked in those that are made from rel- 

 atively sweet curd. In Emmenthaler, or Swiss cheese, 

 the formation of large gas holes is called " blahen." A 

 closely related phenomenon is seen in ' ' nissler J ' forma- 

 tion, where very numerous small holes are formed (thou- 

 sand eyes) . 



The cause of the difficulty has long been charged to 

 various sources, such as lack of aeration, improper feed- 

 ing, retention of animal gases, etc., but in all these cases 

 it was nothing more than a surmise. Very often the 

 milk does not betray any visible symptom of fermentation 

 when received, and the trouble is not to be recognized 

 until the process of cheese- making is well advanced. 



Recent studies from a biological standpoint have, how- 

 ever, thrown much light on this troublesome problem; 

 and, with the cause of these fermentative changes more 

 fully recognized, it is quite probable that improved meth- 

 ods of handling milk will be rapidly introduced that will 

 enable the maker to exclude these troubles. 



176. Relation to living- germs. The formation of 

 gas, either in the curd or after it has been put to press, 

 is due entirely to the breaking down of certain elements, 

 such as the sugar of milk, under the influence of various 

 living germs. This trouble is then a type fermentation, 

 and is therefore, much more widely distributed than it 



