196 ECONOMIC BACTERIA IN MILK AND MILK PRODUCTS 



butter has obtained the prizes awarded for first-class butter. 

 Different cultures will, of course, yield differently flavoured butter. 

 If we desire, say, a Danish butter, then some species like 

 " Hansen's Danish Starter " would be added ; if we desire an 

 American butter, we should use a species like that known as 

 "Conn's Bacillus, No. 41." But whilst these are two common 

 types, they are not the only suitable and effective starters. On 

 many farms in England there are equally good cultures, which, 

 placed under favourable temperatures in new cream, would 

 immediately commence active ripening. 



Jensen makes the following demands regarding a lactic acid 

 culture for creamery use — i. That it will sour the cream rather 

 strongly in a comparatively short time ; 2. That it will thrive at a 

 comparatively low temperature ; 3. That it will coagulate the 

 cream to a uniform homogeneous mixture, and give it a slightly 

 sour taste and odour ; and 4, That it will produce an agreeable 

 aromatic taste and flavour in the butter.^ 



Professor H. W. Conn, who, with Professor Russell, has done 

 so much in America for the advancement of dairy bacteriology, 

 reports a year's experience with the bacillus to which reference 

 has been made, and which is termed No. 41.^ It was originally 

 obtained from a specimen of milk from Uruguay, South America, 

 which was exhibited at the' World's Fair in Chicago, and proved 

 the most successful flavouring and ripening agent among a number 

 of cultures that were tried. The conclusions arrived at after a 

 considerable period of testing and experimentation appear to be 

 on the whole satisfactory. A frequent method of testing has been 

 to divide a certain quantity of cream into two parts : one part 

 inoculated with the culture, and the other part left uninoculated. 

 Both have then been ripened under similar conditions, and churned 

 in the same way ; the differences have then been noted. It is 

 interesting to know that, as a result of experience, creameries have 

 been able to command a price varying from half a cent, to two 

 cents, a pound more for the " culture " butters than for the uninocu- 

 lated butters. The method advised in using this pure culture is 

 to pasteurise (by heating at 155° F.) six quarts of cream, and after 

 cooling to dissolve in this cream the pellet containing bacillus No. 

 41. The cream is then set in a warm place (70° F.), and the 

 bacillus is allowed to grow for two days, and the whole is added 



* Copenhagen Expt. Sta., Bulletin No. 22. 



2 Storr's Agricultural Expt. Sta., Connecticut, U.S.A., Eighth Annual 

 Report, 1895. 



