480 BUTTER 



Zopfii and Bacterium lactis innocuum, are capable of making- 

 milk bitter. Jensen 1 reports Streptococcus casei amari as a 

 cause of bitter milk. Harrison 2 discovered a lactose-fermenting 

 yeast, which he gave the name Torula amara, that produced a 

 bitter flavor in milk and cheese made in Canada. This organism 

 produced an intense bitter flavor in 14 hours. His investigation 

 showed that this yeast grows on the leaves of maple trees and 

 contaminated the milk by being blown from maple trees into 

 the milk cans which stood under these trees on the farms. It 

 was necessary to steam these cans very thoroughly in order 

 to destroy this germ. Conn, Burri, Duggeli, Freudenreich. 

 Govini and others 3 report numerous peptonizing microorgan- 

 isms which are capable of rendering milk and butter bitter. 



Bitter milk and butter frequently also are the result of cer- 

 tain feeds and weeds to which the cows have access, among 

 these we find lupines, rag weed, beet tops, rye pasture (ex- 

 cessive), raw potatoes, and especially many classes of decayed 

 and moldy feed stuffs, and moldy bedding, moldy oat and barley 

 straw. 



Butter may also derive its bitter flavor from the use of 

 chemically impure salt, especially salt containing relatively 

 large amounts of magnesium salts or calcium chloride, or both. 



Butter made from sour cream that has been overneutralized, 

 or improperly neutralized, especially when lime is used as a 

 neutralizer, is prone to show a bitter, limy, or so-called neutral- 

 ized flavor. For proper neutralization which will reliably pre- 

 vent bitterness from this source see Chapter VII on Neutral- 

 ization. 



Oily Flavor. Causes of Oily Flavor. Oily flavor of but- 

 ter is a frequent occurrence in creameries receiving sour cream, 

 pasteurizing at a high temperature and cooling by turning the 

 cream over a surface cooler. Butter which has an oily flavor 

 gives the impression of having, and generally does have, in- 

 ferior keeping quality. Experience has shown that such but- 

 ter, when in storage often, though not always, develops other 

 and more objectionable flavor defects, such as metallic flavor 



1 Orla Jensen. Die Bakteriologie der Milchwirtschaft, p. 82. 



2 Harrison. Landwirtschaftliches Jahrbuch der Schweiz 14, 1900. 

 3 Weigmann. Die Mykologie der Milch, 1911. 



