RIPENING PROCESSES OF CHEESES 139 



Emmental cheese than in other makes. The eyes should only 

 begin to form when the cheese has ripened to such a degree 

 that it is sufficiently plastic to allow of their rounding off ; 

 if they form too soon, they become irregular in shape, and if the 

 mass is made too dry, it will never become sufficiently plastic ; 

 in this state the cheese is known as " Gldsler," having elongated 

 cavities or clefts instead of proper eyes. In order to promote the 

 formation of normal eyes, the cheese is brought into a room at 

 18 to 22 C. when it is two weeks old. Here the ripening process is 

 accelerated and the propionic acid bacteria will gradually develop 

 so that in the course of four to six weeks the eyes will have been 

 fully formed. The cheeses are then brought into a cold place 

 again. As the propionic acid bacteria are very sensitive to sodium 

 chloride, it is possible to regulate the formation of eyes by the 

 addition of more or less salt * ; the chief reason for the adoption of 

 the somewhat troublesome method of dry salting in the case of 

 Emmental cheese, instead of methods by which the cheese 

 receives its full amount of salt at an earlier stage, is doubtless that 

 the cheeses would, in the latter case, only develop small eyes or 

 none at all, as often occurs with small cheeses, which naturally 

 tend to become salted too quickly. If the cheese has not been 

 made sufficiently dry, or contains too many propionic acid bacteria 

 at the outset, the development of the normal eyes will be excessive, 

 and this is a defect which may be just as objectionable as the 

 blowing at an earlier stage, which has been described above. On 

 the other hand, if neither the ripening process nor the development 

 of the propionic acid bacteria have progressed sufficiently in the 

 " warm cellar," it may happen that the eyes will suddenly begin 

 to form at a still later stage ; an after fermentation of this nature 

 will always tend to give a variable product. The pre'sence of 

 unusually large numbers of butyric acid bacteria will also give 

 rise to an abnormal eye formation which, it may be noted, will be 

 of the worst possible type 2 .' In such cases a very energetic 

 butyric fermentation sets in when the cheeses are from ten to 

 fourteen days old, and under these circumstances they will not 

 stand exposure to the temperature of the warm cellar. 



Closely connected with the ripening process is the formation of 

 drops of liquid or " Tears " in the eyes, a process which often first 

 starts when the Emmental cheese is eight months old. The 

 conditions determining the collection of this liquid are, first, that 

 it shall not be too viscous, and second, that the pores of the cheese 

 shall not be too fine. In the ripening of the cheese an appreciable 

 proportion of the dissolved proteins are converted into amino 



1 Orla Jensen, " Landwirt. Jahrbuch der Schweiz," 1906, p. 437. 



2 J. Thoni, " Landwirt. Jahrbuch der Schweiz," 1906, p. 157. 



