Ice Cream
Practical Action
Ingredient control
The milk used to produce the dairy ingredients should be fresh, good quality and free from dirt
and excessive contamination by bacteria. Older milk may impart an unpleasant flavour to the
final product. Technical Brief: Dairy Processing - An Overview gives details of the methods
needed to ensure that good quality milk is used, and Technical Briefs: Butter and Ghee and
Pasteurised Milk describe the quality assurance procedures for making some of the dairy
ingredients. Careful weighing is needed for all ingredients to make sure that the same amount is
used in every batch.
Process control
A process control schedule should be prepared for each product. Table 3 is an example of a
process control schedule for ice cream production.
Stage in process
Activity
Process control points
Weighing/mixing Weigh out ingredients and mix Check ingredient weights (+/-
1g)
Pasteurisation
Heat mixture to destroy micro- Check temperature and time
organisms and enzymes.
(e.g. 72°C +/- 1°C for 10
minutes).
Cool
By immersing vessel in cold
To 4°C +/- 1°C within 20 - 30
water and stirring milk
minutes and store for 4 hours.
Freezing/
In ice cream machine
To - 5°C. Check % overrun.
Aeration
Packaging
Fill into pots or cartons
Check the net weight of each pot
(e.g. 100g +/- 1g)
Seal Seal pots with a foil lid or clip-on Check that the foil seal is
plastic lid
properly formed
Label
Attach label to pots
Check that correct labels are
used, that they are correctly
positioned, and show the correct
use-by date and batch number.
Refrigerate
Harden at -18 to -20°C and store Check freezer temperature.
at this temperature.
Table 3: Process control points in ice cream production
It is particularly important that the temperature and time of heating and cooling the mixture
should be controlled. Over-heating and slow cooling causes changes to the flavour and colour of
the milk, whereas under-heating may lead to survival of undesirable micro-organisms, risking
food poisoning from the product.
Product control
The main quality factors for ice cream are the colour, texture and taste. The colour should
remain unchanged as bright white/cream during processing if colours are not added. The texture
of ice cream can be either soft, or harder and made into blocks.
An understanding of the structure of ice cream is useful to help create the required texture: ice
cream has three components:
1. It is a foam (it has air bubbles in the unfrozen liquid).
2. It is an oil-in-water emulsion (made up of tiny globules of milk fat contained in a
complex water phase)
3. The water phase contains ice crystals and a concentrated unfrozen solution of sugars,
milk solids and other ingredients.
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