342 MICROBIOLOGY OF MILK AND MILK PRODUCTS. 



mproved. This has been found to be true in practice and it is now 

 relieved that pure cultures are of value not only in the ripening of sweet 

 :ream, but that the addition of a relatively large amount of starter to 

 :ream that is already fermented will enhance the value of the butter. 



USE OF PURE CULTURES IN PASTEURIZED CREAM. It is evident that 

 he maker has but imperfect control over the fermentative processes when 

 aw cream is treated with a pure culture. To insure more perfect con- 

 rol the destruction of the contained bacteria and the subsequent inocula- 

 ion of the cream with a pure culture is indicated. The introduction 

 >f the process of pasteurization of cream for butter making was due to 

 )torch. In Denmark this method is used almost exclusively. It has 

 )een introduced into the other dairy countries of the world and is con- 

 ,tantly spreading. Pasteurization combined with the use of the pure 

 :ulture represents the highest type of modern butter making, and where 

 he raw product can be obtained in a fresh condition the butter maker 

 las perfect control over the bacteria that cause the ripening; hence can 

 :ontrol the flavor of the butter, both qualitatively and quantitatively. 



The intensity of flavor of butter is dependent upon the amount of 

 tcid that is developed in the cream or on the ratio between the amount of 

 at and the by-products of the acid fermentation. If these by-products 

 tre small in amount, as in cream having a low acidity, the flavor of the 

 mtter will be low. If the acidity is allowed to reach the maximum, 

 he flavor will be much higher. Thus the maker can control the intensity 

 >f flavor of butter as accurately as he can the kind of flavor. With rich 

 ream, the acidity that can be developed is small and the ratio between 

 he fat and the products of fermentation is low; thus, the flavor of butter 

 nade from very heavy cream is certain to be low. 



PURE CULTURES IN OLEOMARGARINE AND RENOVATED BUTTER. 

 t was previously mentioned that the manufacturer of butter substi- 

 utes employs the same methods to impart butter flavor to his pro- 

 lucts as does the butter maker. The oleomargarine manufacturers 

 mploy pure cultures of lactic bacteria for the fermenting of milk that 

 5 mixed with the fats they employ. The same practice is followed 

 >y the manufacturer of renovated butter. Many of the creameries 

 if the western states receive cream that is shipped long distances, 

 ,nd is collected from the farms but once or twice a week. It is 

 hus in an advanced state of fermentation when it reaches the cream- 

 ry. In order to prepare from this grade of cream, which often has a 



