162 THE BOOK OF BUTTER 



stale or musty flavor may grow in the cream or in the 

 butter. The cowy, dirty, feedy, and bitter flavors may 

 develop through bacterial action. In relation to the 

 feedy flavors, Weigmann and Wolff 1 state : "In studies 

 made of the effect of Swedish turnip, carrot leaves, 

 chives, kohl-rabi leaves, grass, hay, straw, beets, cabbages, 

 and other feeds upon the flavor of butter it was found 

 that changes in flavor were in part due to the taste and 

 odor of the feeds and in part to bacteria found on these 

 feeds which generate new flavors. While it is probable 

 that each group or type of bacteria has a specific action 

 in producing taste and odor, it is not certain if the same 

 feed medium will produce the same taste and odor with 

 different types of bacteria." If these particular bacteria 

 grow in any of the dairy products, it may be assumed 

 'that the growth of certain micro-organisms does intensify 

 the flavor of certain plants. 



The bitter flavor is usually the product of bacterial 

 growth. Wolff 2 writes : " The author found large num- 

 bers of bacteria on the leaves of grass, white clover, and 

 yarrow where cattle were feeding. About 80 per cent 

 belonged to the coli group. Unless the udders of the 

 cows are washed these bacteria may fall into the milk 

 pail in sufficient numbers to cause the bitter taste often 

 noticed." Whether or not Wolff is correct in thinking 

 that these organisms are members of the B. coli group, 

 there is no doubt that in many cases the bitter taste is 

 due to micro-organisms. Many observations show that 

 these organisms grow best at low temperatures, such as 



1 Weigmann, H., and Wolff, A., (Landw. Jahrb.), 46 (1914), 

 No. 3, pp. 343-365, abs. Exp. Sta. Rec., Vol. 32, p. 270. 



2 Wolff, A., The Cause and Nature of Bitter Milk, (Milchw., 

 Zentbl.) 5 (1909), No. 2, p. 67-73; abs. in Chem. Zentbl., 1909, 

 I, No. 11, p. 931. Abs. Exp. Sta. Rec., Vol. 31, p. 379, 1909. 



