Irradiation

Food irradiation involves exposing food to shorter-wavelength ionizing radiation in the form of gamma rays, X-rays, or electron beams as an alternative means of preservation to more traditional methods such as canning. Small doses of irradiation can inhibit food properties such as sprouting or ripening, and larger doses can genetically alter or kill insects and microorganisms that lead to spoilage or human diseases. Irradiated food does not change in terms of appearance, smell, taste, or texture. Nutritional losses during the irradiation process are minimal and are either lower than or equal to nutritional losses from methods such as cooking or freezing. Food irradiation products or facilities can be found in over 30 nations worldwide, including the United States, Canada, Japan, China, Russia, the Netherlands, Belgium, France, and South Africa. Irradiated food does not play a significant role in the U.S. food industry, although research and development are expanding.

The discovery of radioactivity in the late 19th century led to scientific research into its effects and potential uses. French scientists determined in the 1920s that irradiation could be applied to food preservation. The United States did not pursue food irradiation studies until World War II, when the U.S. Army began experimenting with it to meet the challenges of feeding a large military force. Food irradiation is particularly useful in preservation, but it is also used to control sprouting, ripening, mold growth, insect damage, and microorganism [Page 263]control. Food irradiation at higher dosages is used for the sterilization of food for space travel or for hospital use in patients with compromised immune systems. Irradiated foods are still considered perishable, even though their shelf life is extended. Food irradiation at dosages used for consumer products does not sterilize food, so refrigeration and proper food handling and preparation guidelines must still be followed.

These biologists with the U.S. Department of Agriculture's Agricultural Research Service are preparing to irradiate hotdogs packaged in plastic as part of an experiment.

Source: U.S. Department of Agriculture, Agricultural Research Service/Stephen Ausmus

Food irradiation facilities are expensive to build but are generally considered safe. They house electron-accelerator machines that create beams of electrons. The most common source of radiation used in the process is cobalt-60, which is inside a steel casing in a lead-lined chamber. Conveyor belts carry the food through this chamber to complete the irradiation process. The amount of radiation absorbed by food during the irradiation process is known as a dose, which is measured either in the older form of rads or the newer form of grays. The U.S. Food and Drug Administration (FDA) measures doses in kilograys. Irradiation is a cold process, meaning that there is no significant temperature increase in the food during the irradiation process. U.S. food irradiation facilities must meet plant and worker safety guidelines established by the Nuclear Regulatory Commission and the Occupational Safety and Health Administration.

Within the United States, food irradiation is regulated by the FDA and monitored by the U.S. Department of Agriculture. Regulations specify the types of foods that may be irradiated, the radiation dosages that may be used, and labeling requirements for irradiated foods sold in the marketplace. The first FDA-approved use of food irradiation came in 1963 to control insect infestations of wheat and wheat flour. Since that time, approved uses have expanded to include inhibiting sprouting in white potatoes; controlling trichinosis in pork; controlling insects and microorganisms in certain herbs, spices, vegetable seasonings, dry enzyme preparations, packaged fresh or frozen uncooked poultry, and red meat; and inhibiting growth and ripening in a variety of fruits, vegetables, and grains.

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