196 MANAGEMENT OF DAIRY PLANTS 



A butter containing 80 per cent butter fat should, if no losses 

 occur, produce 



(100 — 80) 100 



or 25 per cent overrun. 



80 



Considering that a creamery receives gathered cream con- 

 taining 35 per cent of butter fat, from which is manufactured 

 butter containing 80 per cent of butter fat, the reduction in 

 overrun due to .2 per cent loss in the buttermilk is equal to 

 .4 per cent '■ on the overrun. Miscellaneous losses figured at .2 

 per cent will reduce the overrun .25 per cent. Considering 

 these two losses, we might expect a theoretical legal overrun of 

 25 -(.4+ .25) = 24.35 per cent. 



This overrun is higher than could be expected in general 

 practice, even though no avoidable loss would occur, as it is 

 well known that it is impossible to produce butter which al- 

 ways would contain even 80 per cent of butter fat. It is 

 furthermore recognized that two or more samples may 

 be taken from butter of the same churning, but packed in 

 different containers, and even from the same container and 

 yet differ in excess of one-half of one per cent in fat content. 

 It is therefore only fair to consider that if we have an 80 per 

 cent fat standard, the butter, in accordance with our method of 

 analysis, should contain about 81 per cent of fat. This will 

 reduce the overrun 1.54 per cent, which, subtracted from 24.35 

 per cent, leaves an overrun of 22.81 per cent for gathered cream 

 butter. If whole milk were received and the loss of butter fat 

 in the skim milk amounted to .1 per cent, then the overrun 

 would still be decreased to the amount of 2.73 per cent, or the 

 overrun would in that case be 20.08 per cent. 



Losses Due to Butter Shrinkage. — In the foregoing discus- 

 sion no reference has been made to shrinkage of butter from 

 chum to dealer; this shrinkage varies in accordance with 

 workmanship of the butter, the time of holding, and the tem- 

 perature at which it has been held. A creamery allowing 8 



> Table Xin. 



