in CHEESE 183 



or at the same time, albumoses and peptones. Further changes 

 result in the splitting up of these and the formation of 

 amido-acids, such as phenylamidopropionic acid, leucine, tyrosine, 

 glycocoll, as well as a large number of other compounds, 

 e.g. alanine, amidovalerianic acid, pyrrolidine dicarboxylic acid, 

 aspartic acid, glutamic acid, tryptophane, histidine, lysine, 

 putrescine, cadaverine, guanidine, and succinic acid, finally 

 ammonia also. 



The process of cheese ripening cannot, as regards the 

 changes in the paracasein, be looked upon as decomposition of 

 the proteins, for those substances, e.g. indol, skatol and phenol, 

 which are characteristically formed during such cleavages, are 

 not found in ripening or ripe cheese. 



Volatile fatty acids, such as caproic or butyric are formed 

 during ripening owing to the splitting up of the fat. 1 



The milk sugar which gets into the cheese along with the 

 whey undergoes lactic acid fermentation whilst the cheese is 

 being made and pressed so that after a few days every trace 

 of it has vanished from the fresh curd. The holes found 

 in cheese are due, at least in Emmental cheese, according 

 to von Frendenreich and Orla Jensen, 2 to propionic acid 

 fermentation caused by certain bacteria. In this process 

 the calcium lactate formed by the lactic acid bacteria, is 

 transformed into propionic and acetic acids, and carbon dioxide, 

 the last of which causes the formation of the holes. 

 3C 3 H 6 S = 2C 3 H 6 2 + C 2 H 4 2 + CO 2 + H 2 O 



The above mentioned substances are naturally not the only 

 ones formed during the ripening of the cheese, but they may 

 be appropriately regarded as the mile-stones on the road along 

 which the curd passes whilst being broken down. It is not yet 

 possible by chemical means to isolate and determine all the 

 substances formed during the process of ripening so that for the 

 present little more can be done than to follow the main chemical 

 lines upon which the process is based. Bondzynski 3 has intro- 

 duced the idea of extent and depth in cheese ripening. By extent 

 Bondzynski understands the quantity of curd which is converted 



1 Orla Jensen, "Studier over cle flygtige Syrer i Ost og Bidrag til 

 Ostefermenternes Biologi. " Dissert, Kopenhagen, 1904 ; Landw, Jahrbuch der 

 Schweiz, 1904. 



2 Landiv. Jahrbuch der Schweiz, 1906. 



3 Ibid., 1894, p. 189. 



