BUTTER OVERRUN 275 
The amount of overrun is directly dependent upon the 
following factors: 
Efficiency of skimming and churning. 
Composition of the butter. 
Richness of milk and cream. 
Mechanical losses. 
Correct reading of tests. 
Oty Oo- Wo s 
Efficiency of Skimming and Churning. It is evi- 
dent that the more fat there is lost in skimming and 
churning the lower will be the overrun. To obtain a 
maximum overrun, the loss of fat as shown by the Bab- 
cock test should not exceed 0.05 per cent for skim-milk 
and 0.15 per cent for buttermilk. 
In this connection it should be stated that during the 
summer season it is not at all uncommon to find butter- 
milk testing from 0.3 to 0.5 per cent, largely a result of 
employing too high a churning temperature. 
Composition of the Butter. Besides butter fat, butter 
contains water, curd and salt, and, other conditions the 
same, the greater the amount of non-fatty matter in 
butter the greater the overrun. Water, being present in 
large quantity and subject to considerable variation, very 
appreciably affects the percentage of overrun. There has 
been a tendency among creameries the past few years 
to manipulate butter so as to increase its normal water 
content and thereby increase the overrun. 
The water in butter easily fluctuates between Io and 
15 per cent, and a good overrun can be obtained by keep- 
ing it within the limits of 13 and 14 per cent. 
Salt as a rule has little influence on the per cent of 
overrun because under normal conditions an increase in 
