Research abounds on irradiation.

Irradiation has been under study by Food Safety Consortium scientists for the past few years. The researchers' findings have been reported in scientific publications at various times and have become part of the scientific literature on the subject.

As you know, irradiation preserves food by exposing products to high-energy ionizing radiation. The radiation energy changes the product's molecules, killing microorganisms that could cause spoilage or illness. At Iowa State University, investigators have published summaries of their studies on the dosage of irradiation required to reduce by tenfold the levels of pathogenic bacteria in meat. They found that for the major foodborne bacteria-Salmonella, Campylobacter, Listeria, Yersinia and E. coli O157:H7-the required dosages were 0.04 kiloGray to 0.6 kiloGray, well below both the maximum dosage levels allowed for poultry and the levels sought for beef, pork and lamb. The World Health Organization considers any food irradiated up to an average dose of 10 kiloGrays to be wholesome and safe for consumption.

In one project, a low dose of irradiation killed the spores of Clostridium bacteria that remained in vacuum-packaged beef-based snack sticks after the sticks were exposed to the extrusion cooking process at Kansas State University. In the experiment, nonpathogenic C. sporogenes bacteria were used, but they are as difficult to kill as the pathogenic bacteria. The cooking process had already killed many of the spores. Those surviving spores that were injured could potentially endanger the snack stick, but irradiation at 3.5 kiloGrays delivered the final blow and left no culturable Clostridia remaining.

Kansas State investigators also examined irradiation's effects on the quality of certain meat: boneless pork chops, beef steaks, pre-cooked ground beef patties and raw ground beef patties. The research team found that irradiation did not adversely affect such traits as color, product life, flavor and aroma. Professional flavor profilers assessed the beef steaks for attributes of texture and flavor. They found little to no difference between irradiated and nonirradiated steaks. A panel of consumers reviewing boneless pork chops observed no differences between irradiated and nonirradiated samples while evaluating the chops' qualities.

The University of Arkansas conducted two studies regarding acceptance of irradiated products. A survey that brought responses from 556 food service professionals identified 67.2% as willing to purchase irradiated broiler portions and 67.5% as willing to purchase irradiated beef patties if they were sold at the same prices as USDA-inspected products.

Iowa State researchers test-marketed irradiated chicken at two supermarkets in Kansas in a study that showed about 30% of customers were willing to pay a premium for the product. The marketing included point-of-sale advertising and free samples.

Further information. David Edmark, The Food Safety Consortium, 110 Agriculture Building, University of Arkansas, Fayetteville, AR 72701; phone: [phone]; fax: [phone]; email: [e-mail].