Are Irradiated Foods Still Nutritious?

Irradiation has been compared with pasteurization because it destroys pathogenic bacteria. Because irradiation does not substantially raise the temperature of the food being processed, nutrient losses are small and are often substantially less than nutrient losses associated with other methods of preservation, such as canning, drying, and heat pasteurization and sterilization (7,8,10,11). The relative sensitivity of different vitamins to irradiation depends on the food source, and the combination of irradiation and cooking is not considered to produce losses of notable concern (8).

Proteins, fats, and carbohydrate are not notably altered by irradiation (7,8,12). In general, those nutrients most sensitive to heat treatment, such as the B vitamins and ascorbic acid, are those most sensitive to irradiation. Diehl (8) and Thorne (12) compared nutrient losses from irradiation with those associated with other traditional methods of preparation. Vitamin losses from pure solutions are larger than losses when the vitamin is in a food (8). Nutrient losses can be further minimized by irradiating food in an oxygen-free environment or in a frozen state (8,12). Fox and coworkers (18) derived a formula to calculate predicted losses in cooked pork and chicken on the basis of data on quantities of these items from the second National Health and Nutrition Examination Survey in the US diet and irradiation doses allowed by FDA. Predicted losses for thiamin, riboflavin, and niacin in pork and thiamin in chicken ranged from 0.01% to 1.5%. Earlier reports regarding losses of ascorbic acid in potatoes, due to a shift to dehydroascorbic acid, are no longer considered valid as they failed to consider that dehydroascorbic acid also has vitamin activity (8). In a study of the ascorbic acid content of oranges, Nagai and Moy (19) found no significant differences between irradiated and control fruit at dose levels up to 1.0 kGy and throughout a 6-week storage period.

Sensory qualities such as appearance and flavor have been evaluated in the laboratory (8,17,19,20) and in market studies with consumers (15,20). Consumers consistently rate irradiated fruit as equal or better than nonirradiated fruits in appearance, freshness, and taste (15,20,21).

(From The American Dietetic Association Position: Food irradiation)

Prepared Summer 1997 by Bernadene Magnuson, Ph.D.
University of Idaho, Dept. of Food Science and Toxicology - EXTOXNET FAQ Team.