CHICAGO--Irradiation can effectively eliminate pathogens and reduce spoilage microorganisms while maintaining the wholesomeness and fresh quality of foods, according to the Institute of Food Technologists' Scientific Status Summary "Irradiation of Food" to be published in the January 1998 issue of Food Technology.
Though good farming and manufacturing practices discourage harmful bacteria from entering the food supply, they do not guarantee safety. Irradiation, however, used in conjunction with good practices, can greatly enhance the safety of food and even extend its freshness.
Irradiation is the exposure of food to a source of ionizing (creating positive and negative charges) radiation energy, according to summary author Dennis G. Olson, Ph.D. It disrupts the genetic material of living cells, inactivating parasites and destroying pathogens and insects in food. This includes Escherichia coli O157:H7, Salmonella, Campylobacter, and Trichinella spiralis associated with raw meat and poultry.
Olson noted that irradiation would be extremely effective at eliminating the adulterant E. coli O157:H7, responsible for numerous illnesses and deaths. Consumers who are at high risk for foodborne illness, including children, the elderly, and those with compromised immune systems, would especially benefit from irradiated foods.
By also killing spoilage microorganisms, irradiation extends the freshness of perishable foods, delaying the ripening of produce and preventing the sprouting of vegetables, Olson said. A 1992 study, for example, found that irradiated ground beef stayed fresh nine days longer than non-irradiated beef.
Prior to approving irradiation for specific foods, the radiological, toxicological, and microbiological safety of these applications must be addressed to the Food and Drug Administration's (FDA's) satisfaction.
"With radiological safety, the question is, whether radioactivity will be induced in the food," wrote Olson. "This issue is of no concern for the currently approved radiation sources [gamma rays, electrons, and X-rays] because their energy is too low to induce radioactivity."
Thus, irradiation does not make foods radioactive. It produces a small number of harmless radiolytic products in food that are similar to those formed by cooking, according to Olson. Radiolytic and toxicological review by the FDA has verified the safety of these substances.
Irradiated foods must also demonstrate nutritional adequacy in order to be approved by the FDA. Macronutrients (protein, carbohydrates, and fats) are not significantly affected by radiation doses up to 10 kGy; trace elements and minerals are not affected at all, Olson noted. Minimal vitamin loss may occur depending upon the dose, temperature, presence of oxygen, and type of food irradiated. However, "many food processes, like cooking, alter nutrient content of food much more than irradiation," he wrote. "It is doubtful that any vitamin deficiency would develop from consuming irradiated foods."
There are no major chemical, physical, or sensory changes in foods that have been irradiated. While the color and odor of raw meat may be slightly affected, Olson said, cooking appears to lessen or eliminate the radiation-induced odor, and color changes can be minimized by irradiating meat in an oxygen-free environment in the frozen state.
Successful sale of irradiated food products in four U.S. stores since 1993 shows that consumers will accept irradiated food, Olson wrote. They will accept it more readily when provided with information about the advantages of the technology, according to a 1995 study by Christine M. Bruhn, Ph.D., Center for Consumer Research, University of California at Davis. Irradiated foods marketed in numerous countries were judged superior by consumers and have sold well, noted a 1996 report by the Council for Agricultural Science and Technology.
"Communication with consumers is believed to be critical for expansion of irradiated food markets," Olson concluded.
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