Food irradiation is a form of food processing to extend the shelf life and reduce spoilage of food. We examined the effects of γ radiation on the fatty acid composition, lipid peroxidation level, and antioxidative activity of soybean and soybean oil which both contain a large amount of unsaturated fatty acids. Irradiation at 10 to 80 kGy under aerobic conditions did not markedly change the fatty acid composition of soybean. While 10-kGy irradiation did not markedly affect the fatty acid composition of soybean oil under either aerobic or anaerobic conditions, 40-kGy irradiation considerably altered the fatty acid composition of soybean oil under aerobic conditions, but not under anaerobic conditions. Moreover, 40-kGy irradiation produced a significant amount of trans fatty acids under aerobic conditions, but not under anaerobic conditions. Irradiating soybean oil induced lipid peroxidation and reduced the radical scavenging activity under aerobic conditions, but had no effect under anaerobic conditions. These results indicate that the fatty acid composition of soybean was not markedly affected by radiation at 10 kGy, and that anaerobic conditions reduced the degradation of soybean oil that occurred with high doses of γ radiation.

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Food irradiation using -rays is one of powerful tools to reduce insect infestation in crops and spices. We examined the effects of -irradiation on larvae and adults of Tribolium castaneum. Eclosion for larvae was completely inhibited by irradiation at 500 Gy. A survival rate for adults was markedly reduced by irradiation at more than 500 Gy. The neutral comet assay presented that irradiation irreversibly increased DNA damage at 500 and 1000 Gy and transiently increased DNA damage at 100 Gy, suggesting possible DNA repair in larvae and adults stages. These results indicate that -irradiation at 500 Gy is available to eradicate the beetle at larval and adults stages.