BUTTER AND CHEESE 241 



and also in cream. But as the ripening process proceeds with 

 uniform regularity, the numbers of this organism rapidly increase. 

 Kollin Burr considers these lactic bacteria gain access to the milk 

 from outside sources.* Buttermilk and whey vary much in their 

 bacterial content. 



Butter necessarily follows the standard of the cream. But, as 

 the butter fat is not well adapted for bacterial food, the number of 

 bacteria in butter is usually less than in cream. Butter, when first 

 made, may contain many million bacteria per gramme. After a 

 few days only two or three million may be found, and if butter 

 is examined after it is several months old, it is often found to be 

 almost free from germs; yet in the intervening period a variety 

 of conditions are set up directly or indirectly through bacterial 

 action.f Bancid butter is largely due to organisms. Putrid butter 

 is caused, according to Jensen, by various putrefactive bacteria, one 

 form of which is named Bacillus fmtidus lactis. This organism is 

 killed at a comparatively low temperature, and is, therefore, com- 

 pletely removed by pasteurisation. Hi-flavoured butter may be due 

 to germs or an unsuitable diet of the cow and a retention of the bad 

 quality of the resulting milk. Lardy and oily butters have been 

 investigated by Storch and Jensen, and traced to bacteria. Lastly, 

 Utter butter occasionally occurs, and is due to fermentative changes 

 in the milk, or the presence of acid-producing organisms in the 

 butter such as B. fluorescens liquefaciens, Oidium lactis, and Clado- 

 sporium hutyri (Jensen). Butter may also contain pathogenic 

 bacteria, like tubercle. The B. coli can live for a month in butter. 

 Cheese suffers from very much the same kind of "diseases" as 

 butter, except that chromogenic conditions occur more frequently. 

 Most of the troubles in cheese originate in the milk.| The number 

 of bacteria in cheese is naturally less than that present in milk or 

 cream. The closer texture and consistence of cheese, coupled with 

 the lessened degree of moisture, are sufficient factors to account for 

 this. Nevertheless, cheese contains a considerable number of organ- 

 isms. Adametz found that freshly precipitated curd, moulded in 

 the press and freed from excess of whey, contained between 90,000 

 and 140,000 micro-organisms per gramme, a comparatively large 

 number of them having the power of liquefying gelatine, or, in 

 other words, they possessed a peptonising ferment. During the 

 period of ripening, the bacterial content of the cheese gradually 

 rose to 850,000 in Emmenthaler cheese, and 5,600,000 per gramme, 



* Thirteenth Annual Report of Storr's Agricultural Expt. Sta., Connecticut, 

 1900, pp. 66-81; also Centralh. f. BaU., Abth. ii., 1902, p. 236. 



t Keeping Quality of Butter (L. A. Rogers), U.S. Dep. of Agriculture, 1904, 

 Bull. 57. 



X Board of Agriculture Report on Cheddar Cheese Making (F. J. Lloyd), 1899, 

 pp. 78, 103. 



Q 



