Over Run

The weight of butter obtained from a given lot of cream is always more than the amount of fat present in cream. The amount of butter, which exceeds the amount of fat present in cream is called overrun. In other words, it may be defined as the increase in the amount of butter made from a given amount of fat. It is usually expressed as percentage overrun. The presence of moisture, curd, salt, air, etc., in butter increases the amount of butter. It is a source of profit to the manufacturer and also helps to check the efficiency of the working of the plant. There are several types of overrun which include

i) Theoretical: Theoretically, maximum obtainable overrun in butter is 25% because 80 kg fat yields 100 kg of butter as per PFA standard.

ii) Compositional: It is based on the composition of butter and varies according to the fat content in butter.

iii) Factory: It is calculated on the basis of total packed butter and total fat received in the factory for butter-making.

iv) Churn: This is calculated for a particular type of churn

The formula used for the calculation of Theoretical over-run is given below:

Per cent Over-run (% OR) = (B - F)/F

Where,

B = Quantity of butter made (kg)
F = Fat in churn (kg)

Factors Influencing Over-run:

The following factors affect the over-run in butter:
Inaccuracy in weighing of milk, cream or butter;
 Inaccuracy in fat testing of the samples of milk, cream or butter;
 Fat losses in skim milk and butter milk;
 Fluctuation in fat content of butter;
 Weight allowance in butter packages;
 Handling losses.