How does Food Irradiation Work

Food irradiation is a form of preservation that involves carefully exposing foodstuffs to ionising radiation for a specific length of time in order to destroy any harmful bugs and pathogens that could be lurking on your fruit and veg.

Ionising radiation is a kind of energy emitted by elements with an unstable electrical charge – either positive or negative. The high-frequency, high-energy waves of gamma radiation can penetrate a variety of different materials, drastically altering their chemical makeup, which is why ionising radiation is dangerous to humans.

Ionisation involves bombarding atoms with radiation such as gamma rays to dislodge the electrons in orbit around the nuclei, which results in the atoms becoming charged, or ‘ionised’. The atoms are then called ions. The chemical bonds in ionised bacteria are irreversibly damaged. Once that happens the cell’s genetic instructions stop working, which means harmful bacteria can no longer reproduce.

The irradiation process

Electron beam – A stream of high-energy electrons is fired out of an electron gun. Machine operators remain behind a thick concrete wall while irradiation takes place.

Irradiation cell – This is the chamber through which the food to be irradiated passes. Neither the product being irradiated nor the machine itself can become radioactive and no radioactivity is released into the environment.

Cobalt-60 – Cobalt-6o is the radioactive isotope usually used to irradiate food with gamma rays. This naturally occurring isotope spontaneously decays to its stable state. When not in use it is stored in water, which absorbs the radiation.

Radiolysis – The high energy of ionising radiation striking a microbe breaks the chemical bonds in the bact