FLAVORS OF BUTTER 179 



series 5, in which the acidity was not determined in the 

 first few cans opened, there was no marked change until 

 both bacteria and yeasts had nearly reached their mini- 

 mum number. Of the bacteria persisting for any length 

 of time only the lactic acid group was present in sufficient 

 numbers to be considered as a possible cause." Sayre, 

 Rahn, and Farrand ^ report similar numbers of micro- 

 organisms in butter. 



There are many species of micro-organisms found in 

 butter. Brown ^ asserts that he isolated eighty-eight 

 different species from two samples and these did not 

 include molds or higher forms of bacteria. Of these there 

 were fifty-seven bacteria (cocci, bacilli, or spirilla) and 

 thirty-one yeasts. 



There is a definite relation between the amount of salt 

 in butter and the growth of many of the organisms. 

 Brown ^ states that of the eighty-eight species reported 

 above, twenty-four bacteria and fifteen yeasts grew on 

 a medium when the brine composition is 12 per cent salt 

 and when the incubating temperature is 20° C. (68° F.). 

 Four of these bacteria and six of the yeasts grew well 

 on 12 per cent brine at 6° C. (43° F.). He asserts that 

 12 per cent brine has a much more inhibitive action on 

 the species of liquefying yeasts than it has on the non- 

 liquefiers. It should be remembered that a 12 per cent 

 brine is equal to 1.68 per cent salt in the butter when the 

 latter contains 14 per cent moisture. Giltner and Baker * 

 report that salt to a concentration of 12 per cent does not 



' Sayre, W. S., Rahn, O., and Farrand, Bell, Keeping Qualities 

 of Butter, Mich. Agri. Col. Exp. Sta., Tech. Bui. 1, 1908. 



^ Brown, C. W., Some Actions of Micro-organisms upon the 

 Constituents of Butter, Soi., Vol. 35, No. 893, p. 231, 1912. 



3 Giltner, W., and Baker, J. D., Effect of Salt on Butter Flora, 

 Mich. Sta. Rpt., p. 209, 1915. 



