DAIRY FARMING DAIRYING — AGROTECHNY. 477 



"The butter made from imriiiened nupasteurized cream always developed a 

 cheesy or rancid tiavor. The butter made from ripenal cream, both pasteurized 

 and unpasteurized, developed cold-storage, tishy, and other flavors typical of 

 storage butter. In all cases the overripe butter showed marlied deterioration. 

 The butter made from pasteurized cream without starter usually retained its 

 flavor with little or no change. Even at 32°, where all the ripened butter showed 

 decided changes, the sweet-cream butter deteriorated very little. . . . 



" The difference between butter made from pasteurized sweet cream and that 

 from ripened cream, both itasteurized and unpasteurized, became very marked 

 after holding in a warm room for a short time. Butter made from pasteurized 

 cream with starter added, after the so-called Le Clair or Credicott method, re- 

 tained its fresh flavor better than the ripened-cream butter, but was not quite 

 equal iu keeping quality to that made from sweet pasteurized cream." 



Determinations of bacteria were made, but none were found which could be ex- 

 pected to influence the flavor. 



" In all the butter stored at 10° and —10° there was a gradual decrease in the 

 total bacteria. This was usually slightly more rapid at the higher temperature, 

 but this difference in the rate of decrease was sometimes obscured by errors, due 

 largely to the difficulty of securing a representative sample. At 32° this decrease 

 was usually much more pronounced than at the lower temperatures. In several 

 cases, liowever, there was an actual increase confined chiefly, if not entirely, to 

 the torula group of yeasts. In one package the development was sufficient to 

 make an actual increase in the total number of bacteria, whieli in the ordinary 

 technique includes yeasts as well as bacteria. Usually the growth of yeasts was 

 so much less than the decrease in bacteria that the total number showed a de- 

 crease. It has been demonstrated that some members of this group of yeasts 

 may cause a decomposition of butterfat." 



Butter made from pure cream heated to temperatures high enough to destroy 

 all enzyms developed a rank fishy flavor; hence, it was concluded that the 

 deleterious effect of high acidity was not due to any organism, euzym, or other 

 substance which can be destroyed by heat. Apparently some by-product of 

 Ijacterial growth unaffected by heat had a marked influence on the flavor of the 

 butter, I'robably this was a by-product of the lactic-acid bacteria and the by- 

 product was lactic acid itself. 



When lactic, acetic, and hydrochloric acids were added to different lots of 

 cream the butter made from each lot to which these acids had been added 

 showed undesirable flavors. 



" It would appear, therefore, that the acidity of the cream has a direct 

 influence on the changes in the butter. ... To the person interested in the 

 application of these results to practice it is obvious that butter which market 

 conditions require to be held for any length of time should be made with as 

 little acid as possible. This is especially true of butter held for several months 

 in cold storage and butter canned for use on shipboard or for export to tropical 

 countries." 



The keeping quality of butter made from sweet pasteurized cream was com- 

 pared with that of butter made with a starter. The results showed that when 

 stored at 10° and —10° there was little or no change in the sweet-cream butter 

 over that with the starter, but at 32° there was a decided difference in the 

 flavor of the sweet-cream butter. A comparison was also made with butter for 

 immediate consumption. 



" Tlife difference in favor of the sweet-cream butter was greater in the 

 btitter S or 10 days old at the time of scoring, while in the liutter scored imme- 

 diately after making the highest score was given to the butter with starter. 



