336 MICROBIOLOGY OF MILK AND MILK PRODUCTS. 



and in America. It may be said to be the standard butter of the world 

 since it is the type made in all the great dairy countries. Sweet-cream 

 butter is made especially in southern Europe, and in limited amounts in 

 other countries. 



The intensity and kind of flavor of butter is thus dependent on the 

 acid fermentation of the milk or cream. It is not believed that the fat 

 undergoes any changes during the acid fermentation of the milk which 

 could produce the flavor of sour-cream butter, but rather that the increase 

 in flavor is due to the absorption by the butter fat of certain of the com- 

 pounds formed in the acid fermentation. It is not essential that the fat 

 be present during the acid fermentation in order to impart flavor to the 

 butter. If sweet cream is mixed with sour milk and churned at once, 

 the flavoring compounds are absorbed by the fat from the fermented 

 milk, and the butter will have much the same flavor, both as to intensity 

 and kind, as though the fat had been present during the fermentation. 

 The churning of a mixture of sweet cream and sour milk is used commer- 

 cially and is identical with the methods employed by the manufacturers 

 of oleomargarine and renovated butter to impart flavor to the flavorless 

 fats they employ. It is impossible to recognize these substitutes for butter 

 by their flavor since it is identical with and der ved from the same source 

 as the flavor of butter. 



In the past many ideas have been expressed as to the source of the 

 flavor of butter; some have asserted that it is due, in part, to the decom- 

 position of the proteins of milk by proteolytic bacteria. Both practical 

 experience and experimental work have demonstrated the connection 

 between the acid fermentation of milk and the flavor of butter, and it 

 is certain that what is now considered the finest type of butter can be 

 made from cream in which only acid-forming bacteria (see Chapter I) 

 have grown. 



FLAVOR OF BUTTER. 



CONTROL OF BUTTER FLAVOR. The commercial value of any sam- 

 ple of butter is largely determined by its flavor. If it is lacking in flavor 

 and aroma, or if it has a poor flavor, it brings a low price. The impor- 

 tance of being able to control the flavor, both as to degree and kind, in the 

 manufacture of butter has increased greatly in recent years, because of 

 the introduction of the creamery system, which has largely supplanted 

 the making of butter on the farm. The financial success of any creamery 



