168 THE BOOK OF BUTTER 



The above results have been confirmed by Reakes, Cud- 

 die, and Reid. 1 They report the results of their research as 

 follows : " Pure cultures of organisms isolated from butter 

 having a fishy flavor failed to produce the effect experi- 

 mentally. Butters of fishy flavor were found to contain a 

 high percentage of acid, and it is therefore thought that a 

 high acid may be a contributing factor though not the direct 

 cause of the trouble." It should, therefore, be recognized 

 that the exact source of the fishy flavor in butter is not 

 known, but that there is a positive relation between high 

 acidity of the cream and this taste. Some data seem to show 

 that trimethyl amine is the basic cause of the fishy flavor. 



126. Metallic flavor. This flavor of butter is much 

 like the taste of iron. Very often it is similar to the 

 fishy flavor and usually has a somewhat oily taste. The 

 copper flavor, which is not common, is, of course, metallic. 

 Its taste is rather bitter and is more intense than the char- 

 acteristic metallic flavor of dairy products. These two 

 metals have been studied in this relation, because they 

 are the most commonly used in the construction of dairy 

 apparatus. There are two sources of the metallic flavor 

 in butter : one is by absorption of the metal, and the 

 other is developed by bacterial growth. When the 

 quantity of iron is as small as one part to one million parts 

 of cream, the flavor of the iron is distinct. In the case of 

 copper, only one-half part of the metal to one million parts 

 of cream is sufficient to cause a distinct flavor of the 

 copper. Rogers, Berg, Potteiger, and Davis 2 state, 



1 Reakes, C. J., Cuddle, D., and Reid, H. A., Fishy Flavor in 

 Butter, Jour, of N. Zeal. Dept. of Agri., 4 (1912), No. 1, pp. 1-6. 

 Abs. Exp. Sta. Rec., Vol. 26, p. 778, 1912. 



2 Rogers, L. A., Berg, W. N., Potteiger, C. R., and Davis, B. J., 

 Factors Influencing the Change in Flavor in Storage Butter, 

 U. S. Dept. of Agri., B. A. I., Bui. 162, 1913. 



