4.1.4

Bacterial Contamination

Test yourself

Cross-Contamination

Cross-contamination is the process by which bacteria pass from one food to other foods. Cross-contamination can happen through:

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Food that's already contaminated

  • Contaminated high risk foods contaminating other foods.
  • Raw foods leaking onto cooked foods.
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People

  • Cooking with unwashed hands.
  • Sneezing without using a tissue.
  • Coughing without covering your mouth.
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Cooking utensils and surfaces

  • Not cleaning equipment properly before or after use.
  • Preparing raw and cooked foods on the same surface.
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Pests

  • May plant eggs or excrete onto cooking surfaces.
  • May also contaminate food by landing on it or eating it.

Controlling Bacteria

Untreated eggs and milk are both highly susceptible to contamination. To make these foods safe, we can:

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Pasteurise milk

  • The process involves heating milk to 72°C for approximately 15 seconds.
  • This should destroy pathogenic bacteria before the milk is chilled.
  • All milk must be pasteurised before being sold in UK supermarkets.
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Vaccinate hens

  • Many years ago, the UK introduced a programme for vaccinating hens against salmonella.
  • Eggs and boxes of eggs that have come from vaccinated hens are stamped with the British Lion Quality mark.

Jump to other topics

1Food Preparation Skills

2Food, Nutrition & Health

3Food Science

4Food Safety

5Food Choice

6Food Provenance

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