BACTERIA IN BUTTER-MAKING 193 



financial loss. The factors which tend to have a favourable 

 influence on butter-making, which, though carried out with clean- 

 liness and good management, is not scientifically controlled, are 

 probably of a simple nature. The bacterial species, which give 

 a good flavour, are probably common in a well-kept dair}^, and are 

 more vigorous than the members of the miscellaneous alkaline 

 group. Moreover, the temperature used in ripening cream is 

 found in practice to stimulate the growth of the favourable 

 species of ripening organisms existing normally in a well-kept 

 dairy, or in the milk ducts of a clean and healthy cow. Conn has 

 pointed out that the effect on dairy produce of common bacteria 

 in milk will in measure depend upon conditions, and not simply 

 upon bacterial species. Moreover, there may be natural varieties, 

 in a physiological sense, of one organism, by which different 

 effects will be produced in the butter or cream.^ 



By way of summary, then, we may say that the part which 

 cream-ripening plays in the production of butter may be con- 

 sidered as four-fold. First, ripening makes churning easier and 

 more effectual. Conn accounts for this by suggesting that 

 bacteria soften and dissolve the protein matter connecting the fat 

 globules, and thus cause the fat globules to unite more freely than 

 they do in unripened cream. Secondly, ripening increases the 

 yield of butter, particularly in set cream, and although the increase 

 is small, it becomes not inconsiderable in total amount on a year's 

 working in a large creamery. Thirdly, it is generally held that 

 butter made from properly ripened cream has better keeping 

 properties than that made from unripened or improperly ripened 

 cream. Fourthly, the most important purpose of cream-ripening 

 is the production in butter of a desirable flavour and aroma. It is 

 by this, of course, that butter is judged to be good and market- 

 able, or bad and unmarketable. 



Control of the Ripening" Process 



There are various means at our command for improving the 

 ripening process. Perfect cleanliness in the entire manipulation 

 necessary in milking and dairying, combined with freedom from 

 disease in the milch cows, will carry us a long way on the road 

 towards a good cream-ripening. Recently, however, a new method 

 has been introduced, largely through the work and influence of 

 Professor Storch in Denmark, and Weigmann in Germany, which 



^ Centralb.f. Bakt.^ Bd. v., No. 20, 1899, pp. 665-669. 



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