246 THE FERMENTATION OF CHEESE 



(2) During the period of ripening, the germ content gradually rose to 

 850,000 in Emmenthal cheese and up to 5,600,000 in the "household" cheese, 

 but only a small share in this increase fell to the liquefactive species ; since 

 whilst the quantitative ratio of these to the other (non-liquefactive) kinds was 

 in the fresh curd i : 40, only one colony of liquefactive bacteria was found in 

 150 to 1 80 in the gelatin plate cultures prepared from the ripe cheese. 



The expectation of finding the liquefactive bacteria assume the upper hand 

 during the ripening process was thus dispelled, and the same result was attained 

 in a later research published by E. VON FREUDENEEICH (IV.) in 1894, according to 

 whom the number of lactic acid bacteria in cheese increases with the age of the 

 latter. Hence the chief, if not the sole, share in the ripening of Emmenthal 

 cheese must be ascribed to these lactic ferments. E. J. LLOYD (I.) also came to 

 the same opinion in his researches on the ripening of Cheddar cheese. 



The reason why Duclaux, in his earlier investigations, arrived at a contrary 

 result will be readily understood when it is remembered that he prepared his 

 pure cultures exclusively by the dilution method, and therefore by the aid of 

 liquid nutrient media (bouillon in particular) ; since in this last-named liquid the 

 organisms of the genus Tyrothrix thrive exceedingly, whereas the lactic acid 

 bacteria grow badly, if at all, therein. Consequently mixed sowings in this 

 medium result in a preponderance of the liquefactive species described by 

 Duclaux. From the discovery made by FREUDENREICH and SCHAFFER (I.) that 

 the ripening of hard Swiss cheese also goes on uniformly throughout the mass 

 when air is excluded, it follows that the said lactic acid bacteria are (facultatively) 

 anaerobic. 



The harmonious results of the researches of M. LANG and FREUDENREICH (I.) 

 with Swiss, and of E. MARCIIAL (III.) with Belgian (Limburg), samples show 

 that a principal part in the ripening of soft cheese is taken by O'idium lactis, 

 further particulars of which member of the Eumycetes group will be found in the 

 second volume. Various budding fungi also seem to aid in the process, but more 

 detailed information on this point is absent. According to the statements of 

 JUL. HENRICI (I.), Swiss cheeses are poor in yeast-like fungi and rich in bacteria ; 

 but the converse ratio has been shown to exist in American cheeses. 



Odour is one of the chai-acteristics peculiar to individual kinds of cheese ; it 

 is but slightly developed in many, but is prominent in others. In isolated 

 instances it is produced by the mechanical incorporation of added flavouring 

 substances to the fresh cheese mass. This applies, for instance, to the already 

 mentioned " Glarner Schabziger " or herb-cheese (Krauter Kase), which owes its 

 characteristic aroma to the addition of dried Melilotus cterulea (blue or Swiss 

 melilot). The English " sage-cheese " and American " clover-cheese " may also 

 be mentioned as examples. 



In many cases the odorous principle is, on the other hand, produced 

 spontaneously in ripening, i.e. by the activity of micro-organisms, of which 

 nothing is as yet difinitely known. L. PAMMEL (II.) discovered on cabbnge 

 leaves a Bacillus aromaticus which, when inoculated into fresh curd, produces 

 during the ripening process an aroma similar to that of "clover-cheese." 



178. Pure Culture Ferments. 



The results briefly recorded in the preceding paragraph must be regarded as 

 first steps inspiring us to further progress towards the goal of all methods 

 relating to the practical application of Fermentation Physiology, viz., the 

 establishment of control over the progress of fermentation. In the matter of 

 cheese-making the attainment of this desire is still remote, and Mycologists are 

 not yet able to recommend this or that particular microbe with any assurance of 



