Some food is exposed to radiation before it is sold. This is called irradiation.
Why food is irradiated
High doses of radiation kill microorganisms or insects in the food. This makes the food safer to eat. The radiation damages the organisms’ genetic material, so that they can no longer survive or multiply. This is like pasteurisation, which makes food safer by destroying bacteria in the food. And unlike pasteurisation, irradiation can be used on solids as well as liquids.
Low doses of radiation stop plant foods sprouting and delay ripening. It changes the biochemistry of the food. This makes the food last longer.
How irradiation works
Food is irradiated by exposed it to ionising radiation. Two kinds of ionising radiation can be used: gamma rays and electron beams.
The gamma rays used to irradiate food come from cobalt-60. Cobalt-60 is a radioactive form of the metal cobalt. It’s produced by irradiating cobalt in a nuclear reactor.
Electron beams are generated by electricity, and can be turned on and off. They don’t come from a radioactive source.
Irradiation does not make food radioactive
- Both kinds of irradiation use radiation that can’t make foods radioactive.
- When using gamma-ray irradiation, the food never comes into direct contact with the cobalt-60. This stops it getting contaminated.