Irradiation depleted three of eight nutrients in salad greens by small amounts in a new study of the effects of the controversial food santization process.The Agricultural Research Service study of two popular baby-leaf spinach cultivars found that irradiation decreased ascorbic acid, or Vitamin C, by 42 percent. Irradiation converted vitamin C to an oxidized form called dehydroascorbic acid, which provides the same benefits as vitamin C inside the leaf, according to the researchers.
Levels of lutein/zeaxanthin, and B-carotene, which make up 80 percent of all carotenoids in spinach, were reduced on average by 12 percent in the salad leaves.
Four nutrients -- folate, Vitamin E, Vitamin K and neoxanthin -- exhibited little or no change in concentration with increasing levels of irradiation during the study.
For the study, the two spinach cultivars were grown, harvested, sanitized and packaged according to industry practices. Each cultivar was packaged in both air or nitrogen gas as used by industry to extend shelf life. The cultivars then were exposed to up to 2.0 kiloGrays (kGy) of radiation in 0.5 kGy increments.
Irradiating salad leaves after washing has been shown to reduce harmful and non-harmful microorganisms. The U.S. Food and Drug Administration has approved up to 4 kGy of irradiation for fresh iceberg lettuce and spinach.
Source: Agricultural Research Service, USDA
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