PACKING BUTTER 373 



held for one hundred days at 23 C. showed no increase in acid- 

 ity. From these results Rogers concludes that the causal rela- 

 tion of physical agents such as heat and moisture to changes 

 of the butter is excluded. In the case of non-sterile canned 

 butter examination showed a marked change in the texture and 

 flavor. The changes were gradual; when about 25 days old, a 

 distinct off-flavor was noticed which increased in intensity, un- 

 til, at two hundred and ninety-seven days in one case and at 

 two hundred and fifty-one days in another, there was a disagree- 

 able, fishy flavor and a strong penetrating odor. There was also 

 a correspondingly slow increase in the acidity. Micro-organ- 

 isms which consisted almost entirely of lactic acid bacteria, a 

 comparatively small number of Torula yeasts and a few lique- 

 fying bacteria decreased rapidly until there were present only 

 a few spore-forming liquefying, bacteria. Owing to this marked 

 decrease in germ life, Rogers attributes the increase in acidity 

 and the off-flavor to the probable action of fat-splitting enzymes. 



Weigmann 1 in a very extensive investigation studied the 

 keeping quality of butter made by different processes and sealed 

 in tin cans, samples of which were placed on board of German 

 men-of-war and which were returned and examined at intervals 

 of six, twelve and eighteen months. These results demonstrated 

 that there is a great variation in the keeping quality of different 

 lots of butter and that while prolonged storage under unfavor- 

 able temperature conditions tended to intensify the deterioration 

 of the butter, a few of the samples packed in tin cans returned in 

 excellent condition even after eighteen months' travel. While 

 Weigmann's results were not conclusive and while his funda- 

 mental aim was to determine that process of manufacture which 

 would produce the best keeping butter, the data secured demon- 

 strated that under certain ideal conditions of manufacture, butter 

 packed in tin cans has remarkable keeping quality. 



In the canning of butter the tin plate used should be coated 

 with shellac or enamel to protect the can against the action of 

 the acids and the brine of the butter and to guard the butter 

 against rapid deterioration as the result of such action. While 

 tin itself is an inert metal that does not yield to the action of 



1 Weigmann, "Versuche zur Bereitung von Dauerbutter" Milchwirtschaft- 

 liches Zentralblatt, Vol. 44. Nos. 23 and 24, 1915. 



