Irradiation, one of the more controversial methods to enhance the safety of the nation's food supply, was recently approved for use with red meat.

"Food irradiation is perhaps the only food preservation method that has been extensively studied for safety for over 40 years, before people began to use it," said Dr. Aubrey Mendonca, a microbial food safety research scientist with North Carolina A&T State University's School of Agriculture. "It has been found to be safe by a World Health Organization expert committee on the wholesomeness of irradiated foods."

According to Mendonca, the World Health Organization committee reviewed over 200 well-designed studies involving humans as well as animals, before concluding that irradiated foods did not cause any toxic or genetic defects.

"The committee recommended irradiation of food up to a dose level of 10 kiloGray," said Mendonca. "Many countries have permitted the use of this dose level for irradiation of meat, fish, vegetables, fruits and grains, but, in the United States, the Food and Drug Administration only recently approved irradiation for red meat."

Though limited amounts of irradiated fruits, including mangoes, papayas, and strawberries, are being marketed in the United States, Mendonca attributes the hesitancy of the United States in approving the method for red meat to misdirected consumer fears.

"It is well known among scientists that each modern food processing advance, such as pasteurization, canning, and freezing, produced criticism," said Mendonca. "By far the greatest barrier to the more extensive use of food irradiation is not technical but sociological. This sociological barrier exists in the form of consumer resistance and distrust, much of which can be linked to inadequate information as well as false information."

Specific fears mentioned by Mendonca include that irradiation will make food radioactive, and that it might be used by food processors to treat poor quality food.

"Irradiated food is not radioactive, and food irradiation, just like any other food preservation process, cannot produce superior quality food from inferior quality raw material," said Mendonca, who points out that similar objections were raised by some groups opposing the use of pasteurization for treatment of raw milk.

"It was believed that pasteurization would be used to mask inferior quality in milk, and would encourage poor food preparation practices," Mendonca said. "However, this did not prove to be true because the use of milk pasteurization by the food industry has caused production standards and microbiological quality of raw milk to be higher than they have ever been."

Mendonca does acknowledge that high doses of radiation can cause undesirable changes in foods, such as rancidity in foods containing fats and oils and softening of fruits and vegetables. However, irradiation of foods in a frozen state has been shown to minimize rancidity. In addition, efficient regulation, similar to regulatory methods for other food processing technologies such as heating and freezing, can be important in minimizing undesirable changes in foods subjected to irradiation.

The food irradiation process involves exposing foods to gamma rays from a radioactive source such as cobalt-60, or to electron beams and X rays from linear accelerator machines.

When food is irradiated, it absorbs energy from irradiation. This absorbed energy destroys harmful microorganisms by penetrating microbial cells and destroying their ability to reproduce, which results in death for the microorganism.

"It is important to note that irradiated foods are not radioactive, and food irradiation does not change the molecular structure of foods any more than cooking, canning, or freezing," said Mendonca. "Irradiated foods also bear a special logo with the words 'Treated with Radiation' or 'Treated by Irradiation' so that consumers can make informed buying decisions."

According to Mendonca, food irradiation offers important benefits for both consumers and the food industry, because it extends the shelf-life of food and enhances food safety by destroying spoilage and pathogenic microorganisms in food. This translates into safe wholesome foods for consumers, and reduced economic loss due to spoilage for food producers, since between one quarter and one third of the world's food supply is lost due to post harvest spoilage.

Irradiation can also:

• destroy foodborne pathogens such as Salmonella, E. coli O157:H7. Campylobacter jejuni, Listeria monocytogenes, and Cyclospora.
  
• destroy foodborne insects as well as parasites, such as Trichinella.
  
• prevent sprouting in potatoes and onions.
  
• reduce liability of food industries for food contamination by pathogenic microorganisms.

"Everyone wants safe food," said Mendonca. "And, though it's not perfect, irradiation seems to be one viable means of achieving this."

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For more information, please contact Dr. Aubrey Mendonca, NC A&T School of Agriculture, (336) 334-7328.