Calculation of Batter- and Cheese Yield. 183 



in the skim milk and the butter milk, and how much 

 water, salt and curd the butter will contain. 



217. Calculation of overrun. The overrun is calculated 

 by subtracting the amount of butter fat contained in a 

 certain quantity of milk, from the amount of butter made 

 from it, and finding the per cent, which this difference is 

 of the amount of butter fat in the milk. 



Example: 8000 Ibs, of milk is received at the creamery on a 

 certain day; the average test of the milk is 3.8 per cent. ; 340 Ibs. 

 of butter was made from this milk, as shown by the weights of 

 the packed tubs. By a simple multiplication we find that the 

 milk contained 8000X. 038=304 Ibs. of butter fat. The difference 

 between the weight of butter and butter fat is, therefore, 36 Ibs. ; 

 36 is ^^ -=11.8 per cent, of the quantity of butter fat in the 

 milk; that is, the overrun for the day considered was 11.8 per 

 cent. 



The formula for the overrun is as follows: 

 y._(b-f) 100 



x_ -j- 



b and / designating the quantities of butter and butter 

 fat, respectively, made from or contained in a certain 

 quantity of milk. In the preceding example, the calcu- 

 lation would be as follows: (840 ~^ 4) 10 = 11.8 per cent. 



In gathered -cream factories the overrun will naturally 

 come higher than in separator creameries, since no loss 

 of butter fat in the skim milk occurs in the former. The 

 overrun based on the amount of fat in the cream will not 

 under average creamery conditions be likely to vary 

 much from 18 per cent. 



218. Conversion factor for butter fat. A committee of 

 the Association of American Agricultural Colleges and 

 Experiment Stations at the ninth annual convention of 



