THE RELATION OF MICROORGANISMS TO BUTTER 415 



the maker seeking to regulate these so that the culture shall be ripe at 

 the desired time each day. 



Use op Pure Cultures in Raw Cream. — ^The cream as it reaches 

 the creamery contains a greater or less number of acid-forming bac- 

 teria that ultimately will cause it to ripen and the flavor of the butter 

 will be due to the by-products of the mixture of bacteria. If, through 

 the addition of a pure culture, the relative number of organisms that 

 are known to be favorable is greatly increased, the flavor of the product 

 should be improved. This has been found to be true in practice and 

 it is now believed that pure cultures are of value not only in the ripen- 

 ing of sweet cream, but that the addition of a relatively large amount 

 of starter to cream that is already fermented will enhance the value 

 of the butter. 



Use OF Pure Cultures in Pasteurized Cream. — It is evident 

 that the maker has but imperfect control over the fermentative proc- 

 esses when raw cream is treated with a pure culture. To insure more 

 perfect control the destruction of the contained bacteria and the 

 subsequent inoculation of the cream with a pure culture is indicated. 

 The introduction of the process of pasteurization of cream for butter 

 making was due to Storch. In Denmark this method is used almost 

 exclusively. It has been introduced into the other dairy countries 

 of the world and is constantly spreading. Pasteurization combined 

 with the use of the pure culture represents the highest tj^e of modem 

 butter making, and where the raw product can be obtained in a fresh 

 condition the butter-maker has perfect control over the bacteria 

 that cause the ripening; hence he can control the flavor of the butter, 

 both qualitatively and quantitativdy. 



The intensity of flavor of butter is dependent upon the amount 

 of acid that is developed in the cream or more correctly on the ratio 

 between the amount of fat and the by-products of the acid fermenta- 

 tion. If these by-products are small in amount, as in cream having a 

 low acidity, the flavor of the butter wiU be low. If the acidity is 

 allowed to reach the maximum, the flavor will be much higher. Thus 

 the maker can control the intensity of flavor of butter as accurately 

 as he can the kind of flavor. With rich cream, the acidity that can 

 be developed is small and the ratio between the fat and the products 

 of fermentation is low; thus, the flavor of butter made from very heavy 

 cream is certain to be low. 



