Contamination Definitions

Food Contamination refers to food that has been infected or polluted.  This means that the quality in food has been affected and the food may no longer be safe.


It is the responsibility of all food establishments to ensure their food is free from contamination and is safe to eat.


Types of contamination:

  • Allergen cross contamination
  • Chemical contamination
  • Microbiological contamination
  • Physical contamination


Allergen Cross Contamination

Allergen cross contamination is traces of allergic food ingredients within a product that are not declared on the packaging.  Allergen contamination is a potential risk for consumers of high-risk allergies.


List of allergenic food ingredients that are or may be present at site:

  • Cereals such as wheat, barley, etc.
  • Crustacea and their products
  • Egg and their products
  • Fish and their products
  • Milk and their products
  • Lupin and their products
  • Peanuts and their products
  • Sesame and their products
  • Soybean and their products
  • Tree nuts and their products


Chemical Contamination

Chemical contamination refers to substances that are not a natural part of the food and may be poisonous.  They may enter the food through carelessness or poor handling, the environment, equipment, or from natural sources.

  • Disinfectants, detergents, sanitisers
  • Heavy metals such as mercury, zinc, cadmium, lead
  • Pesticide, insecticide, fertiliser residues


Microbiological Contamination

Microbiological contamination is living, single-cell organisms, which may spoil food or cause disease.  They are not visible except through a microscope and enter the food through poor hygiene and handling of food or the environment.  By allowing good food safety practices, the food handler can eliminate or minimise these hazards.  There are four categories of microbiological contamination: bacteria, fungi, parasites, viruses.

Bacteria: Bacteria are found everywhere.  Most bacteria are harmless, and some are used in food production such as yoghurt and cheese.  Some bacteria cause food spoilage, but there are a number of species of harmful bacteria, such as Salmonella, which can cause disease.

Fungi: There is a number of fungi that produce toxic substances known as mycotoxins.  One particularly hazardous fungus is aflatoxins.  Mycotoxins can be absorbed by consumption of the contaminated grain or indirectly by consumption of the contaminated animal who is infected with mycotoxins.

Moulds are a common cause of food spoilage.  They can be found in a variety of foods such as bread, cheese, dips, and fruit and can be seen as small spots or furry growth on the surface of food.  They can tolerate acidic and low temperature foods.

Yeasts are not known to cause food-borne illnesses; however, they do spoil food such as fruit juices, jams, and cheeses producing a moist or slimy appearance and smell.  Yeasts are commonly used in food production such as beer, bread, and wine.

Parasites: Parasites are transmitted to humans via contaminated water or foods.  It is a common issue in tropical countries.  Algae and protozoa are parasites of key public concern.

Viruses: Viruses require a live host to grow and multiply.  They may be present in food through contaminated people or contaminated water.


Physical Contamination

Physical contamination refers to parts of non-food items that are found in food.  They may come from machinery, equipment, the environment, personnel, or pests.  Examples are glass, hair, pest droppings, jewellery, metal fragments, paper, plastic, stones, twigs.


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