Food Irradiation - General Information
What is food irradiation?
Food irradiation is a food processing technology that exposes certain types of food to a source of ionising energy. Under the standard covering the irradiation of food in Australia and New Zealand, this energy can be in the form of Cobalt 60 sourced gamma rays, machine generated X-rays, or an electrically generated electron beam.
Electron beam and X-ray technology allows the beam to be switched on and off. It does not use radioactive material. Gamma rays are generated from a radioactive source. In the case of food irradiation this is usually Cobalt 60.
Gamma rays are similar to the energy used in microwave ovens, but they have a shorter wavelength. They pass energy through food in the same way that microwaves do, but in this case the food remains cool. The rays themselves are not radioactive.
Does irradiated food become radioactive?
No. When the treatment stops, energy does not remain in the food. Where a radioactive Cobalt 60 source is used, the gamma rays do not have enough energy to make food radioactive. Also, the food does not come into contact with the energy source, so it cannot become contaminated by radioactive material.
Why is food irradiated?
Irradiation is a food preservation process. Food is irradiated to destroy bacteria that cause food decomposition and food poisoning. Those bacteria include the parasites, moulds and yeasts that spoil food, and salmonella and campylobacter that cause illness.
More traditional preservation methods are used for the same reason. They include drying, smoking, salting, curing, canning, freezing or pasteurisation. As with irradiation, they keep food safe to eat by delaying the natural decomposition processes that result from bacterial action.
Different preservation techniques are used with different types and forms of food.
For example irradiation can be used to treat herbs and spices in place of chemical treatments. It can also be used to destroy the unwanted pests that can accompany food when it is traded regionally or imported from other countries.
What happens when food is irradiated?
All food preservation methods change the composition of the food in some way. Some change the taste, appearance, texture, composition and nutritional value of the food more than others do.
In the case of irradiation, different doses have different effects.
At low doses, irradiation lengthens the shelf life of fruits like strawberries by destroying moulds and inhibits sprouting in vegetables like potatoes. At higher doses, irradiation helps to kill the bacteria and pathogens that cause food poisoning.
When food is cooked or preserved in any way, its composition changes and new compounds form. Research has shown that, in the case of irradiation, the change in the chemical composition of the food is minimal. Many of the resulting compounds are the same as those formed when food is cooked or preserved in more traditional ways.
Is irradiated food safe to eat?
The consensus among scientists worldwide, after more than forty years of research into the safety of irradiated foods, is that irradiation produces food that is safe to eat when it is carried out in accordance with specified standards. This research has included multigenerational animal studies and studies using volunteers who ate only irradiated food.
Three international agencies, the World Health Organization, the Food and Agricultural Organization of the United Nations, and the International Atomic Energy Agency accept that food irradiation is a safe and a useful processing tool. The American Dietetic Association has stated that, ' as with pasteurisation, the evidence suggests that food irradiation can make a quality food supply better' .
Irradiation cannot turn bad food into wholesome food and it is not a substitute for the good manufacturing practices necessary to produce food that is safe to eat. These practices must still apply. Irradiated food will begin to spoil in the same way as food preserved in other ways, once the packaging is removed or it is exposed to new sources of bacterial contamination or the spores of yeasts and moulds.
Is irradiation used elsewhere in the world?
More than forty countries allow the use of irradiation for food safety reasons. As examples: most of the frogs legs sold in France are irradiated; most of the herbs and spices sold in South Africa have been irradiated; and in Thailand there is growing demand for irradiated Nham, a fermented pork sausage that is usually eaten raw.
The labelling requirements vary, however, from country to country. Some like the European Community require the labelling of any food that contains an irradiated ingredient, however small the percentage of that product. This is also the case in Australia and New Zealand. In the United States, labelling applies only where the whole food item is treated.
Some Sources of Additional Information and Reference Material
American Dietetic Association (2000) Position of the American Dietetic Association: Food Irradiation. Journal of the American Dietetic Association 100, pp246-253 (www.eatright.org)
International Organization of Consumers Unions (now Consumers International) (1994) Food Irradiation: Solution or Threat. Briefing Paper No.3 (www.consumersinternational.org)
International Consultative Group on Food Irradiation (1999) Facts about food irradiation
Separate Fact Sheets provide information onStandard A17- Irradiation of Food and the Herbs & Spices Application. These are available from www.foodstandards.gov.au.
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