TREATMENT OF CREAM PREVIOUS TO THE CHURNING. 225 



found in buttermilk. C. 0. Jensen states that the lactic- 

 acid bacteria even succumb at about .75 per cent acidity. 

 Too sour starters may therefore cause a great deal of 

 damage first of all because injurious bacteria have been 

 allowed to multiply in them. When these reach the cream 

 they are again placed under unfavorable conditions, but even 

 if they are not allowed to multiply there to any appreciable 

 extent they will be present in relatively large numbers and 

 go over into the small gatherings of liquids in the butter. 

 The acidity will easily increase farther and butyric-acid 

 bacteria, if present, will start their fermentation rancid, 

 spoilt butter being the result. Other bacteria, as those of 

 " oily butter," may in the same way be propagated from 

 the starter to the butter. It is therefore of the greatest 

 importance to keep the fermentations in the starter in 

 check. No bacteriological analyses or other intricate 

 methods are necessary to determine when the starter is 

 done and when the fermentation should be stopped by 

 cooling. A skilled butter-maker can easily determine the 

 question by taste, odor, and appearance of the starter.* 



The proper ripening of the cream is, as has often been 

 stated, one of the most difficult problems of dairying, since 

 it can very easily fail or be influenced by exterior condi- 

 tions. It is above all essential here as everywhere else to 

 observe the most minute cleanliness, and to watch all one's 

 movements to prevent any possible infection to the cream. 



At many places the cream is run directly from the sep- 

 arator into the ripening-vat; but this method is to be re- 

 jected, as all kinds of irregularities in the ripening of the 

 cream will easily then arise whereby the solidity and grain 



* See foot-note on p. 227, 



