432 BUTTER, CHEESE, ETC. 



consist of aqueous liquid ; in many cases where the globules are 

 of sufficient size for the surface energy to become small, they 

 cease to be spherical. 



The reason that butter always does, and must, contain water 

 is that the aqueous liquid present is finely divided, and assumes 

 a spherical condition. It is impossible by pressure from the 

 outside to remove small spheres from a homogeneous medium. 



It appears certain, from the experiments of Storch on the 

 density of butter, that the density of the fat is the same as that 

 of butter fat in the solid state ; it is, therefore, solid in butter. 

 This view is nearly universally accepted. 



With the recognition of the fact that butter is an approxi- 

 mately homogeneous fatty substance, the reason for its change 

 of consistency by alteration of temperature at once becomes 

 apparent. To churn butter of the right consistency it is neces- 

 sary that the fat in the cream shall be of that consistency. As 

 pointed out by the author and S. 0. Richmond, the fat in cream 

 which has been warmed solidifies very slowly. If the cream has 

 been kept at a high temperature, as in summer, it is necessary 

 to churn at a lower temperature than if the cream has been 

 kept at a low temperature, as the effect on the consistency of the 

 fat of cream of cooling for a long time at a fairly low temperature 

 is the same as that of cooling for a shorter time at a lower tem- 

 perature. 



Temperature of Churning. The best temperatures for 

 churning are as follows : 



Recently separated cream (quick churning), about 8 C. (46-4 F.) 

 (slow churning), 13 C. (55-4 P.) 



Sour cream, whiter, . . . ". 18 C. (64-4 F.) 

 summer, . . . 13 C. (55-4 J F.) 



If the butter be churned at too high a temperature, it will 

 contain more water than at medium temperatures. Butter 

 churned at very low temperatures also contains more water than 

 at medium temperatures ; this appears to be due to the fact 

 that in the one case the fat is too liquid, and in the other too 

 solid, for the maximum effect of squeezing out the watery portion 

 on working to be attained. Butter which is quickly churned by 

 violent impact also has a tendency to contain more water than 

 that churned more slowly. This may be explained by the 

 hypothesis that if the nuclei are quickly formed several globules 

 of fat may coalesce simultaneously and enclose more buttermilk 

 than if they coalesced singly. 



When the cream churned is very sour the solids not fat may 

 contain precipitated casein : in this case the ratio of solids not 

 fat to water is high. 



