The Food Irradiation Process

(From The American Dietetic Association Position: Food Irradiation)

Irradiation exposes food to radiant energy. Food is passed through an enclosed chamber - an irradiator - where it is exposed to an ionizing energy source (Figure 2). Although the sources of ionizing energy may be gamma rays from cobalt 60 (60Co) or cesium 137 (137Cs), x-rays, or electrons generated from machine sources (7,8), food irradiation in the United States relies exclusively on the use of (60Co) (9,10), which is contained in stainless-steel rods placed in racks. The gamma rays emitted are very short wavelengths, similar to ultraviolet light and microwaves. Because gamma radiation does not elicit neutrons (ie, the subatomic particles that can make substances radioactive), "meltdown" and chain reactions cannot occur, and irradiated foods and their packaging are not made radioactive (8,10-12). The (60Co) gamma energy penetrates the food and its packaging but most of the energy simply passes through the food, similar to the way microwaves pass through food, leaving no residue. The small amount of energy that does not pass through the food is negligible and is retained as heat.

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Prepared Summer 1997 by Bernadene Magnuson, Ph.D.
University of Idaho, Dept. of Food Science and Toxicology - EXTOXNET FAQ Team.