190 BACTERIA IN BUTTER AND OLEOMARGARINE. 
mark butter is always made from pasteurized cream, and this 
makes it necessary to use an artificial starter, since pasteurized 
cream will not ripen of itself. The pasteurization destroys practi- 
cally all of the acid bacteria, and, as we have learned, when the acid 
bacteria are absent the putrefying bacteria are quite sure to develop. 
Hence, pasteurized milk requires an acid starter to insure a proper 
ripening. 
In Unpasteurized Cream. By this method the starter is 
simply added to the ordinary cream. The use of starteis in this 
way is open to a theoretical objection. The cream already con- 
tains bacteria in large numbers and, ordinarily, in considerable 
variety. These would themselves produce the ripening of cream, 
even without any starter. The effect of the starter added to the 
cream already filled with bacteria will, evidently, not always be 
uniform. It might produce little or no effect, or, if the starter is 
added in considerable quantity, it might overcome the effect of the 
smaller number of bacteria originally in the cream. In practice it is 
found that the use of starters does have this latter effect, and in most 
cases,- there is a noticeable improvement in butter made from cream 
thus ripened. The results, however, are not absolutely uniform, 
and even with the use of a large amount of starter it will sometimes 
happen that the bacteria present in the cream will have more in- 
fluence than those of the starter, and the butter will suffer. 
The use of cultures in unpasteurized cream was first begun in the 
United States and has been more widely adopted here than any- 
where else. Butter made from unpasteurized cream is not so 
uniform as that made from pasteurized cream, but the butter made 
in this way is, at least to the American taste, superior to butter made 
'with pasteurization, due probably to the fact that pasteurization 
prevents the growth of miscellaneous bacteria that ordinarily 
occurs before the lactic bacteria develop. Pasteurized cream butter 
is somewhat milder in flavor than that made from unpasteurized 
cream, and the American market demands a flavor somewhat 
stronger than that which is popular in Europe. Hence, to the 
American taste, up to the present time, the butter from pasteurized 
cream is not superior to that made from unpasteurized cream. 
