BUREAU OF ANIMAL INDUSTRY. 



219 



BUTTER INVESTIGATIONS. 



The work pertaining to changes in storage butter has been con- 

 tinued with some progress. The effect of metalhc salts on cream has 

 been studied, with the result that 20 parts of a metal salt in a milhon 

 parts of cream show a distinct influence on the flavor of the butter, 

 copper being more active than iron. These investigations have 

 already shown that deleterious effects were obtained when acid 

 cream was used. More recently it has been found that when oxygen 

 is run through a ffask of milk containing metal salts a strong odor is 

 produced in a short time. All these facts support the hypothesis that 

 the principal changes in storage butter are due to the catalytic action 

 of metal salts produced by the action of acid cream on cans, vats, 

 and other containers in inducing an oxidation of some constituent of 

 the butter. This hypothesis can not be definitely estabhshed as yet, 

 but recent results are very encouraging. A method has been perfected 

 for measuring the gases in butter, and by this means it is hoped that 

 oxidation can be measured. 



An effort has been made to establish a method of determining lime 

 in butter when used as a neutralizing agent. 



For the purpose of establishing the normal composition of cream- 

 ery butter, upon which more satisfactory standards may be based, 

 about 1,000 samples of butter have been analyzed during the year. 



During the past season butter made from unpasteurized ripened 

 cream (the usual method), from pasteurized ripened cream, and from 

 pasteurized sweet cream was stored and compared, and the results 

 again showed the superior keeping qualities of that made from pas- 

 teurized sweet cream. This butter was free from fishy or other 

 storage flavor. The results are summarized in the following table: 



Comparison of storage butter made by different methods. 



Method. 



Raw cream, ripened 



Pateurized cream, ripened 

 Pasteurized cream, sweet. 



Initial score 

 (average). 



92.4 

 93.4 

 92.9 



Storage 

 tempera- 

 ture. 





 10 

 20 





 10 

 20 





 10 

 20 



Score after 



storage 

 (average). 



87.3 

 86.9 

 86.3 

 91.2 

 90.3 

 88.3 

 92.4 

 91.9 

 91.4 



In studying the relative cost of making butter from pasteurized 

 and unpasteurized cream the results indicate that no more coal is 

 used in making it from the pasteurized than from the raw cream, and 

 the difference in ice is comparatively small. 



The investigations looking to the production of dried cultures for 

 use in butter and cheese making have been handicapped by the fact 

 that a patented process is involved; but aside from this process it 

 has been found possible to produce dried cultures containing 50,000,000 

 cells per gram, and this is a very great improvement over the cultures 

 usually found on the market. This work will be continued and will 



