No. 4.] USE OF PURE CULTURES. 173 



bacteria are propagated day after day, and a uniform flavor 

 is to be expected. There are, however, in this method of 

 Avork such a large number of species of bacteria that often- 

 times the worse species gain such a prominence that an ob- 

 jectional)le flavor results. Whenever an undesirable flavor 

 develops, butter-makers seek to overcome the difliculty by 

 seeding their cream with fresh stock, procured from a 

 neighlioring creamery or dairy which is known to develop 

 good flavor. 



I have in mind a case reported a short time since of a 

 creamery where the fresh-gathered cream was pumped up 

 into the tempering vats. The butter produced was of an ex- 

 ceedingly agreeable flavor, until the pump was overhauled 

 and cleaned. It was found to l)e covered with a sour slime in- 

 side, full of bacteria. The removal of this filth and slime, with 

 its content of organic life, was virtually "killing the goose 

 that laid the golden egg," for the butter made afterwards 

 showed a loss of the flavor for which it had been esteemed. 



A step taken by many German butter-makers, at the sug- 

 gestion of scientific investigators, was to discard natural 

 ripening for ripening by cultures carefully selected for the 

 fine flavor they imparted to l)utter. There are several 

 preparations in use in Germany for desirable fermentation 

 of cream, as well as for agreeable fermentation of beer. 



In America there are two pure cultures on the market for 

 producing uniformly fine-flavored butter, knoAvn as " Lactic 

 Ferment," prepared by Chr. Hansen; and "Bacillus 41," 

 by Professor Conn. The latter was isolated from a sample 

 of sterilized milk, brought from Uruguay, which had been 

 improperly preserved. The claims made for these artificial 

 ferments are three : — 



1. Uniformity of Product. — As the same culture is re- 

 newed from day to day, or every week, the, same varieties 

 of bacteria always develop, and the flavor of the butter 

 remains very uniform. 



2. Increase in Flavor. — Not only is the product more 

 uniform, but the "quick, high flavor" so much prized is 

 secured with certainty by use of the proper ferment. 



3. Improving the Keeping Quality. — Weigmann and 

 Storch found that butter of extremely fine flavor rarel}- kept 



