Processing food

Preserving food

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The cold chain

How did we develop the use of cold to preserve food?

Cold plays a key role in long-distance transportation. It makes food produced in other regions of the world, such as fresh fruit and vegetables, dairy products and meat, more widely available.


In the 19th century, techniques for making artificial cold developed very quickly. They used air, water or gas such as ammonia to produce cold.

What is the difference between freezing and deep-freezing?

Deep-freezing reduces the temperature of food rapidly whereas freezing does not. The resultant ice crystals are finer and so food retains its texture and flavour.

What is the cold chain?

The cold chain refers to the steps that must be carried out to produce frozen food, such as packaging, transportation and storage. We can only prevent bacteria from developing if we respect the cold chain.

Why should we never refreeze food?

If we refreeze food after it has thawed or been defrosted, we are breaking the cold chain. Bacteria will develop very quickly and could make us ill.

 

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