WHAT SHOULD THE ox'ERRUx 01' cri;a,m i;k\- i!i:? i:>.j 



in creameries is calculated as described pre\i()usl}'. The formula 

 is as follows : 



Butter -fat 



-. Xioo = i)er cent of actual o\-errun. 



tat 



Calculation of Churn-yield. — Instead of expressing the 

 increase of butter o\'er that of fat in the percentage o\errun. 

 as above, it is often customary among creamerymen to speak 

 of the " churn-yield." For instance, the}- say that their test was 

 3.90, and their churn-yield was 5. meaning that on the average 

 each 100 j)ounds of milk contained 3.9 pounris of fat and Aielded 

 5 pounds of butter. The churn-}-ield is alwa}'s expressed in per- 

 centage, and is obtained b>' di%-iding the total pounds of butter 

 obtained by the total pounds of milk from which the butter was 

 made, according to the following formula: 



Pounds of butter 



^^^ , r — ^11 " X 100 = churn-\'ield. 



Pounds 01 milk 



In case cream is handled instead of milk, the same ma\- be 

 obtained by substituting " pounds of cream " for " pounds of 

 milk " in the formula. 



What Should the Overrun in a Creamery Be? — In discussing 

 this problem we shall take So per cent as the legal standard for 

 fat in butter. If every churning of butter were to drop to this 

 standard, but none below it — a thing quite imjjossible of attain- 

 ment — if the patrons were credited with all the fat the creamer}' 

 received, and if there were no mechanical losses, and no fat in the 

 buttermilk, then e\-ery So pounds of milk-fat recei\'ed would 

 make 100 pounds of butter; that is, 100 pounds of fat would 

 make 125 pounds of butter, or, the overrun would be 2^ per cent. 



The creamery has some gains and some losses which tend to 

 offset each other. 



The gains come mainly from two sources, namely, (i) a small 

 fraction of a pound of cream on some, but not all, of the cans of 

 cream. (2) A small fraction of a per cent of fat on some, but not 

 all, of the cream tested. 



