204. BACTERIA IN BUTTER AND OLEOMARGARINE 
terium known has all these characteristics, but a mixture, such as 
a natural starter, may have them. On the other hand, if a 
creamery notices the development of “off tastes” in the butter, 
the best method of removing them is by the use of a commercial 
pure culture. Both kinds of starters thus have their advantages. 
THE USE OF STARTERS 
In Pasteurized Cream.—If the cream is first pasteurized so as 
to destroy most of the bacteria present, the added starter will have 
a free chance to grow. The pasteurizing of cream is simple and 
not very expensive, and it produces a medium largely free from 
bacteria. The use of starters in pasteurized cream has become 
practically universal in Denmark and some of the other countries 
of Northern Europe. There are two reasons for this: (1) A higher 
and more uniform grade of butter can be obtained in this way. 
(2) The prevalence of tuberculosis has brought about the enact- 
ment of a law requiring all milk that goes through the creamery 
to be pasteurized in order to destroy the tuberculosis germs. For 
this reason Denmark 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 practically 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 starters 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 
