238 THE ARTIFICIAL SOURING OF CKEAM. 



which were formerly attributed exclusively to bad fodder. In 

 this case also bacteriologists have been able to confute erroneous 

 opinions and render valuable assistance to practice. 



There is probably not a single dairy in North Germany or 

 Denmark whose butter has not at some time or other been " oily," 

 i.e. exhibited a flavour recalling that of mineral oil. This malady 

 appears with particular frequency in dairies deficient in appliances 

 for keeping the souring cream and finished butter sufficiently cool. 

 Weigmann showed that both the acid generator (prepared by 

 spontaneous acidification) and the butter-milk of such dairies are 

 very impure, in a bacteriological sense, and he was invariably 

 successful in remedying the complaint by the introduction of 

 artificial souring. 



A second and not less injurious defect is the so-called turnip 

 flavour. Butter suffering from this complaint has a repulsive 

 sweet taste, recalling that of turnips. To throw the responsibility 

 on the latter is an obvious, but not always justifiable, procedure, 

 since cases are known where neither the cows nor any of the dairy 

 appliances had come into contact with turnips, notwithstanding 

 which the flavour still made its appearance in the butter. C. O. 

 JENSEN (I.) discovered, in 1891, in the milk of several Jutland 

 dairies where this complaint had long been rife, a microbe which 

 he named Bacillus foetidus lactis, and which was recognised as the 

 cause of the malady. This motile bacillus has a breadth of 0.4- 

 0.6 ju,, its length varying usually between 0.9 and 1.5 ju, and often 

 attaining 5.5 /x. No spore formation has been detected, and the 

 organism does not liquefy nutrient gelatin. As its second name 

 implies, this bacillus gives rise to stinking decomposition in milk, 

 but is not the only species producing the same complaint, Jensen 

 himself having grouped along with it a number of others possess- 

 ing the same power, among them being several species of micro- 

 coccus (not more definitely named), a Merismopedium, &c. The 

 employment of pure cultures of lactic acid bacteria gave satisfac- 

 tory results, producing a pure and fine-flavoured butter in place of 

 the previously almost unsaleable article. 



A third evil which is probably (though not yet indubitably) 

 attributable to bacteria, is the so-called fishy or train-oil flavour 

 in butter. Other defects, such as greasy, tallowy, cheesy butter, 

 have their origin in the inferior chemical composition of the 

 cream ; whilst for a third group of complaints, e.g. stable smell 

 and smoky smell, the uncleanliness of the milker is responsible. 



How firmly the injurious bacteria settle themselves in the 

 rooms of the infested dairies is evident from the observations 

 made by Ronneberg, according to whom the beneficial results 

 accruing from the employment of pure cultures of acid bacteria 

 in infested dairies are only temporary, and disappear if fresh 

 supplies of the invigorating pure culture are not introduced in 

 good time. 



