EXPERIMENT STATION BULLETINS. • 417 



lactic acid might be decomposed into butyric acid or some other acid, but 

 its proportion is always very small. Still, it does not need very much 

 butyric acid to cause a very disagreeable taste. The lactose., however, in 

 the amount present, is not very likely to be decomposed into substances 

 with a pronounced odor and taste. Certainly the protein substances are 

 most apt to give bad tasting and smelling compounds, and some investi- 

 gations along this line are being carried on in this laboratory; so far, how- 

 ever, without positive results. 



The comparison of the scores of the samples with and without Bad. lactis 

 Connii, Bad. I. cochleatus, Oidium ladis, and the liquefying yeast did not give 

 any decided results. The samples are too different in their production to 

 allow final conclusions. The most proper way of testing the influence of 

 these organisms upon butter is the churning of sterile cream with pure cul- 

 tures and mixed cultures as Jensen did. 



We made several series of butters in this way, but alm.ost all of them had 

 contaminations of bacteria or molds. These experiments will be repeated 

 again, though it seems exceedingly difficult to get a product which can be 

 called butter, free from contamination. 

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