Overrun is usually
defined as the volume of ice cream obtained in excess of the volume of the mix.
It is usually expressed as “percent overrun”. The increased volume is composed
mainly of air incorporated during the freezing process. The amount of air which
should be incorporated depends upon the composition of the mix and the way it
is processed and is regulated so as to give that percent overrun which will
give proper body, texture and palatability to the ice cream. Too much air will
produce a snowy fluffy ice cream while too less air on the other hand will lead
to soggy, heavy ice cream.

i)

**How to obtain and control overrun**: The following factors need to be considered in determining the amount of overrun in ice cream.- Legal regulation enforced in the market area.
- Total solids content of the ice cream mix.
- Type of ice cream to be made (fruit/nut ice cream etc.)
- Selling price of ice cream.
- Type of packages.

The overrun
attainable at the freezer depends upon the following points:

- Type of ingredients used in the mix.
- Sharpness of scrapper blades.
- Speed of dasher.
- Volume of refrigerant passing over freezing chamber.
- Temperature of refrigerant

The use of proper
overrun tester will ensure uniform overrun. The control of overrun is very
important and should be maintained as nearly constant as possible from batch to
batch.

ii)

**The per cent overrun:**The percent overrun in different types of ice creams is given in Table
iii)

**Failure to obtain the desired overrun:**Due to the following factors one fails to obtain overrun in ice cream- Longer time to obtain overrun.
- Too high drawing temperature.
- Very soft ice cream.
- Tendency to form ice cream with coarse texture because of large is crystal formed.

iv)

**Method of calculating percent overrun:**There are following two methods by which the percent overrun can be calculated.
1)
By volume

% Overrun =
((Volumeof ice creasm)-( Volumeof mix))/( Volumeof mix)*100

10 litres of ice cream mix are frozen to make 19 litres of ice cream” What is the overrun in the ice cream.”

Volume of ice cream
mix = 10 litres

Volume of ice cream = 19 litres

% Overrun
= ((Volumeof
ice creasm)-( Volumeof mix))/( Volumeof mix)=((19-10)/(10))*100

=90%

2) By
weight

Weight of unit Weight of same unit

((Volumeof mix – Valumeof ice cream)/
(Weight of unit valume of ice cream))*100

Weight of 100 ml of
ice cream mix = 110 gm

Weight of 100ml of
frozen ice cream = 55 gm

What is the %
overrun in ice cream?

Wt. of unit vol. of mix –Wt. of same
unit vol. of ice cream

% Overrun =((Wt.of
unit vol.of mix –Wt.of same unit vol.of ice cream)/( Weight of same unit
volumeof ice cream))*100

((110-55)/55)*100 = (55/55)*100 =100%

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