THE CAUSE OF PUFFY ("BLOWN") CHEESE 249 



complaint and the means of preventing and combating it have been dis- 

 covered. 



181. The Cause of Puffy (" Blown ") Cheese. 



The naturally obvious hypothesis that pitting is due to the gas-producing 

 powers of microbes was experimentally confirmed by H. WEIGMANN (VIII.) in 

 1 890. Undoubted though it be that inflation is also a result of microbial activity, 

 it is, nevertheless, equally undecided whether the malady is caused by specific 

 ferments, or only differs from normal pitting in degree, i.e. arises from the same 

 cause. 



Of the two possible methods of explanation here indicated, the first is 

 championed by ADAMETZ and FREUDENREICH (VI.) in particular. The latter in 

 1890 established, in the case of three species of bacteria recognised as setting 

 up inflammation of the udder in cows, and named Bacillus Guillebeau, a, b, c, 

 after their discoverer that when inoculated into fresh curd they produce 

 inflation and bad flavour. The fermentative activity and products of these 

 three microbes were minutely examined by A. MACFAYDEN (I.) and L. NENCKI 

 (I.). The gas evolved by B. G. c. is a mixture of carbon dioxide and hydrogen, 

 their relative proportions at the climax of fermentation being about 76 : 23, 

 but afterwards becoming so far modified that, at the close of fermentation, only 

 0.72 per cent, by volume of hydrogen is found in the gas. To these three 

 injurious organisms (pathogenic in cows and goats) a fourth was soon afterwards 

 added by FREUDENREICII (VII.), viz., Bacillus Schafferi (bacteriologically very 

 similar to Bacterium coli commune) which was first obtained as a pure culture 

 from "puffy" cheese, and subsequently also found in "Nissler" cheese. 

 Freudenreich consequently regarded this bacillus as the cause of both these 

 maladies in cheese, and explained its dual manner of working by stating that 

 puffiness is produced when the fresh cheese curd contains comparatively few 

 colonies of this bacillus, at considerable distances asunder, but of large size, 

 and therefore capable of liberating much gas; whereas, on the other hand, 

 " Nissler " cheese results when the microbe is distributed abundantly, as individual 

 cells, throughout the ripening mass. ADAMETZ (VII.) found in the milk and 

 cheese of a. Sornthal dairy a fission fungus which he named Micrococcus 

 Sornthalii, and which proved capable of causing puffiness in cheese. This 

 microbe is shown in Plate I. Fig. i. 



The second method is founded on a different basis. Whereas Freudenreich 

 devoted his attention to the discovery of specific inflation ferments, FR. BAUMANN 

 (I.), on the other hand, endeavoured to ascertain the external conditions under 

 which a microbe producing the normal pitting of cheese would become the cause 

 of inflation. An example of this is afforded by the Bacillus diatrypeticus casei, 

 discovered by him. This organism, when sparsely inoculated in curd prepared 

 from Pasteurised milk, produces a "blind" cheese, i.e. one containing merely 

 a few holes ; but when it is added in large amount, it gives rise to puffiness. 

 This facultatively anaerobic fission fungus is a non-motile capsule bacillus 

 generally 1.5 p. in length and 0.7 p in breadth ; a photographic representation 

 is given in Plate I. Fig. 2. In media containing sugar it liberates a gas chiefly 

 consisting of carbon dioxide along with a not inconsiderable portion of hydrogen ; 

 and in addition to these products alcohol and lactic acid are formed. 



If this bacillus be inoculated into fresh curd prepared from non-Pasteurised 

 milk, and consequently rich in a variety of bacteria, a struggle ensues between 

 them. In presence of a superior force of species that do not generate gas, the 

 B. diatrypeticus casei is suppressed, and " blind " cheese will result. On the 

 other hand, when the restrictive power of the other organisms is merely sufficient 

 to moderate, but not prevent, the development (and consequently gas-producing 



