374 CHEESE 



to the greatest and most serious extent in cheeses of the 

 Emmenthal and Gruyere types, which are manufactured 

 from somewhat sweetish curd. 



Sometimes the holes appear in the early stages of 

 manufacture, the curd in such instances containing 

 enough gas to make it float in the whey. Frequently, 

 however, the trouble only shows itself when the cheese is 

 in the press or in the ripening room. 



The organisms which are responsible for the majority 

 of " gassy " cheeses are varieties of Bact. colt or Bact. 

 lactis aerogeneS) especially those which give rise to much 

 gas when grown in milk-sugar media. 



Bad. S chaff eri and Bact. Guillebeau of Freudenreich 

 belong to this class, and other organisms closely allied 

 to Bact. lactis aerogenes have been isolated and shown to 

 be the cause of " blown " cheese and bubbly curd by 

 Peter, Schneebeli and others. 



Bolley and Hall found a close relationship between 

 this trouble and contamination of the milk with cow- 

 dung, and this appears to be specially true when the 

 latter comes from animals suffering from digestive dis- 

 turbances, brought on by the consumption of wet grass, 

 clover, and other succulent green foods. 



There is some evidence that some of the organisms 

 associated with mastitis or inflamed udder sometimes 

 have a causal connection with spongy curd. Bs. Guillebeau^ 

 Freud., and Micrococcus Sornthalii, Adametz, are said to 

 possess this double character. 



Certain varieties of the butyric acid organisms and 

 yeasts probably give rise to gassy cheeses also. Various 

 methods are adopted to get rid of gassy fermentation in 

 cheese. 



Every effort should be made to reduce contamination 



