Food irradiation

Food irradiation refers to a process where food is exposed to a type of radiation called ionizing radiation . The high-energy of the radiation, which can come from a radioactive or a non-radioactive source, breaks apart the genetic material of microorganisms that are on the surface of the food. Microorganisms and other surface contaminants, including insects , are killed as a result.

This scrutiny of food irradiation, combined with the public controversy surrounding the exposure of foods to radioactivity, has meant that the effects of irradiation on foods have been extensively studied. The consensus from these studies is that radioactive sterilization of food does not cause the food itself to become radioactive, nor does the irradiation appreciably alter the nutritional characteristics of the food.

The practice of irradiating foods is not new. Patents were issued in the United States and Britain for food irradiation in the first decade of the twentieth century. Scientists demonstrated in 1947 that meat and other foods could be sterilized by ionizing radiation. The military took a great interest in this development, seeing it as a way of supplying field troops with food. Military experiments on the irradiation of fruits , vegetables , milk and milk products, and various meats began in the U.S. in the 1950s.

In 1958, the U.S. Food and Drug Administration became the official government agency concerned with the evaluation and approval of irradiated foods. Congress gave the FDA authority over the food irradiation process.

The manned space program undertaken by the U.S. beginning in the 1960s gave a great boost to food irradiation technology. Astronauts have always eaten irradiated foods. In addition, in the 1960s, the United Nations established a Joint Expert Committee on Food Irradiation. The committee concluded in 1980 that the irradiation of foods posed no unique nutritional or microbiological problems.

Irradiation methods

Food irradiation can be accomplished in three different ways, using three different types of rays: gamma rays, electron beams, and x rays . Gamma rays are given off by the radioactive elements cobalt and cesium. Gamma rays are powerful, and can penetrate through several feet of material. As such, precautions against technician exposure to the radiation are necessary, and a special irradiation chamber is needed.

Electron beams are not as powerful as gamma rays. They can penetrate to depths of a few centimeters. Nonetheless, they are excellent for the sterilization of surfaces. Electron beam sterilization of medical and dental equipment has been routine for decades. Additionally, electron beams are not radioactive.

X-ray irradiation of food was introduced in the mid–1990s. X rays are a blend of the other two techniques, in that x rays are as powerful and penetrating as gamma rays. But, like electrons, x rays are not radioactive.

Foods such as solid meat and poultry, and fresh produce are well suited to irradiation sterilization. Not all foods, however, are as suited to the irradiation process. Eggs, milk, and shellfish, for example, should be treated by another process to best preserve their quality. Food irradiation alters the taste or appearance of some varieties of grapes , lemons, and nectarines. Irradiation is no substitute for proper cooking and storage. Even irradiated food can become contaminated if it is improperly cooked or stored.

Food irradiation sparks debate

Like biotechnology , food irradiation has sparked fierce public debate. Some scientists are ardent supporters
while other public groups are detractors of food irradiation. Supporters of food irradiation contend that its widespread use has the potential to reduce death and illness internationally due to food-borne microorganisms such as salmonella in poultry and trichinosis in pork.

Salmonella causes four million people to become ill and results in 1,000 deaths annually in the United States alone. Contamination of food products with a bacterium called Escherichia coli 0157 causes over 20,000 illnesses and 500 deaths a year. Internationally, as much as 30% of the world's food supply cannot be used each year because it is either spoiled or consumed by insects. Globally, there are an estimated 24,000–120,000 cases of Salmonellafood poisoning and 4,900–9,800 cases of E. coli 0157:H7 food poisoning each year. Treatment of such food-borne illnesses and lost productivity costs an estimated US$5–6 billion each year.

Despite the weight of evidence and the need for a more effective food treatment strategy, advocates of food irradiation face public opposition. Some consumers and groups are concerned about the unforeseen reactions in food caused by the presence of high-energy particles. Others do not want the food they eat to have been exposed to radioactive substances. Ultimately, the benefits of food irradiation will be weighed against the public's wariness concerning radiation and the food supply.

As public awareness and understanding of irradiation continues, the acceptance of irradiation as a food protection strategy could prevail. The weight of evidence supports the technique. As of 2000, food irradiation is endorsed by the United States Food Protection Agency, the American Medical Association, and the World Health Association, and over 40 countries sterilize food by irradiation.

See also Bacteria; Deoxyribonucleic acid (DNA); Food preservation.

Resources

books

Satin, Morton. Food Irradiation: A Guidebook. Lancaster, PA: Technomic Publishing Company, 1993.

periodicals

Osterholm, M.T., and M.E. Potter. "Irradiation Pasteurization of Solid Foods: Taking Food Safety to the Next Level." Emerging Infectious Disease 3 (1997): 575–577.

Radomyski, T., E.A. Murano, D.G. Olson, et al. "Elimination of Pathogens of Significance in Food by Low-dose Irradiation: A Review." Journal of Food Protection 57 (1994): 73–86.

other

Centers for Disease Control and Prevention. 1600 Clifton Road, Atlanta, GA 30333. (404) 639–3311. <http://www.cdc.gov/ncidod/dbmd/diseaseinfo/foodirradiation.htm.>.

Brian Hoyle

KEY TERMS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Carcinogen

—Any substance capable of causing cancer by mutating the cell's DNA.

Free radicals

—Unstable molecules containing an odd number of electrons and, therefore, seeking an electron from another molecule.

Gamma ray

—A highly penetrating type of radiant energy that has the power to ionize.

Ion

—An atom or molecule which has acquired electrical charge by either losing electrons (positively charged ion) or gaining electrons (negatively charged ion). The process of changing a substance into ions is known as ionization.

Radioisotope

—A type of atom or isotope, such as strontium-90, that exhibits radioactivity.

Radiolytic

—Products or substances formed during the radiation process.