Irradiation preserves nutrients in food and kills microbes that destroys them. The preservation technique exposes food to electron beams or gamma radiation, a high-energy light stronger than the X-rays your doctor uses to make a picture of your insides.
Gamma rays are ionizing radiation, the kind of radiation that kills living cells. Ionizing radiation can sterilize food or at least prolong its shelf life by
Killing microbes and insects on plants (wheat, wheat powder, spices, dry vegetable seasonings)
Killing disease-causing organisms on pork (Trichinella), poultry (Salmonella), and ground beef (pathogenic E. coli)
Preventing potatoes and onions from sprouting during storage
Slowing the rate at which some fruits ripen
Irradiation does not change the way food looks or tastes. It does not change food texture. It does not make food radioactive. It does, however, alter the structure of some chemicals in foods, breaking molecules apart to form new substances called radiolytic products (radio = radiation; lytic = break).
About 90 percent of all compounds identified as radiolytic products (RP) also are found in raw, heated, and/or stored foods that have not been deliberately exposed to ionizing radiation. A few compounds, called unique radiolytic products (URPs), are found only in irradiated foods.
Many scientific organizations, including the 27,000-member Institute of Food Technologists and an international Expert Committee on the Wholesomeness of Irradiated Foods (which includes representatives from the United Nations, the International Atomic Energy Agency, and the World Health Organization), believe that irradiation is a safe and important weapon in the fight against food poisoning caused by microbial and parasitic contamination.
The Food and Drug Administration has been approving various uses of food irradiation since 1963. In addition, irradiation is approved for more than 40 food products in more than 37 countries around the world.
Some consumers, however, remain leery of irradiation, fearful that it may expose them to radiation (it can’t; no radioactive residues are present in irradiated food) or that URPs (unique radiolytic products) — compounds produced only when foods are irradiated — may eventually turn out to be harmful.
Around the world, all irradiated food is identified with this international symbol. Just in case that isn’t enough to get the message across, the package must also carry the words “treated by irradiation” or “treated with irradiation.” The only exception is commercially produced food that contains some irradiated ingredients, such as spices. The symbol and/or wording isn’t required, for example, on the packaging for a frozen pizza that’s seasoned with irradiated oregano.