108 Thirty-Sixth Annual Report of the 



which does not contain these lighter oils does not get rancid. 

 When oleo is heated it has a lard flavor, but when good butter is 

 heated it has the rich odor peculiar to good butter. This is 

 possibly due to these oils being driven off. Oleo manufacturers 

 use all the methods of ripening known to the buttermaker to 

 produce flavor, but there is a great gulf between the two that 

 cannot be bridged by the use of starters. Good milk or cream 

 kept for several days can not by any or all the arts of pasteur- 

 izing and ripening with pure cultures produce that rich nutty 

 aroma so much desired. This lies, I believe, largely in the char- 

 acter of the fat, and may make a difference of at least six or seven 

 percent in the value of the product. 



Renovated butter stands in the same class with oleo, for the 

 heating employed in the renovating process tends to drive ofT 

 the volatile substances which seem to give butter fat its quality. 



Now let us consider the churning of the fat. The plasticity 

 of the fat is an important factor. The process of churning is a 

 process of bumping the fat globules together. If they are very 

 plastic they unite quickly. If we get below a point of plasticity 

 they will refuse to unite. The red hot horse shoe that the old 

 ladies used to drop into the churn to drive out the witches 

 raised the temperature to the point of plasticity. The patent 

 churn that brings butter in three to five minutes requires plastic 

 fat to accomplish this result. 



But there is another important factor in churning. The fat 

 globules must be close together but not too close. Thin cream 

 requires a comparatively high temperature to bring butter. The 

 fat globules are so far apart that the bumping does not stick 

 them together readily. Even when high temperatures are used 

 the smaller globules are left behind when the large ones are 

 gathered and the considerable quantity of buttermilk is rich in fat. 

 If the fat globules in the cream are close together they bump more 

 readily, the smaller ones have less chance of escape, and the 

 smaller volume of buttermilk is relatively poor in fat. If how- 

 ever the cream contains more than 40 percent of fat the globules 

 are so close together that after a little bumping the irregular 

 masses of fat refuse to pass and the cream revolves with the 

 churn. It is then necessary to add enough water to separate the 

 particles in order to let them pass. Cream for churning should 

 contain about 35 percent of fat in order to miss this point of 

 sticking together, — of being too thick on the one hand, and on the 

 other of too much loss of fat if it is too thin. 



A buttermaker churns three or four hours at 54° F. — tlie 

 summer temperature, before the butter comes. He raises it 

 three degrees, following a suggestion from an expert, and it 

 comes in forty minutes. The buttermaker had forgotten that 



