CHURNING 271 



another. If it were not for the obstructing presence in the cream 

 of this air, cream would churn more rapidly. It is obvious that 

 in a vacuum, or under reduced pressure, the churning- process 

 would occupy much less time. 



Since it is during the churning process and not during the 

 working process, that the bulk of the air found in the finished 

 butter, is incorporated, and since the presence of air in butter 

 represents an active agent of butter-deterioration, churning in 

 vacuo, aside from grealy reducing the churning period and in- 

 creasing the capacity of the creamery, would tend to exert a 

 markedly favorable effect on the keeping quality of the butter. 



Under certain conditions, which render cream excessively 

 viscous, such as is the case in cream from stripper cows, or 

 very cold /cream, or cream that has undergone ropy-milk fermen- 

 tation, the churning process is very much prolonged and fre- 

 quently it does not reach the breaking point at all, because 

 of the air-holding and whipping properties of the abnormal 

 viscosity of such cream. For this same reason, any agency, or 

 condition that reduces the viscosity, hastens the churning pro- 

 cess. Thus, sour cream churns more quickly than sweet cream, 

 the acid destroying the viscosity and the whipping power of the 

 cream. Cream from cows which have been in milk for a short 

 time only churns more rapidly than cream from stripper cows, 

 because the former is more fluid and less viscous. At a high 

 churning temperature, provided that the temperature remains 

 below the melting point of fat, cream churns quicker than at 

 a low temperature, because a rise in the temperature increases 

 the fluidity of the cream. 



In this stiff and rigid cream the emulsion of fat-in-skim 

 milk is still intact. 



Why Butter "Breaks" Suddenly. As the butter granules 

 become larger in size in the thickened cream, a point is reached, 

 where the surface of the butter granules becomes so small in 

 proportion to their cubic contents, that the fat-in-skim milk 

 emulsion can no longer be sustained, the emulsion is broken. 



