ESR spectroscopy for detecting gamma-irradiated dried vegetables and estimating absorbed doses

In view of an increasing demand for food irradiation technology, the develo pment of a reliable means of detection for the control of irradiated foods has become necessary. Various vegetable food materials (dried cabbage, carr ot, chunggyungchae, garlic, onion, and green onion), which can be legally i rradiated in Korea, were subjected to a detection study using ESR spectrosc opy. Correlation coefficients (R-2) between absorbed doses (2.5-15 kGy) and their corresponding ESR signals were identified from ESR signals. Pre-esta blished threshold values were successfully applied to the detection of 54 c oded unknown samples of dried clean vegetables (chunggyungchae, Brassica ca mestris var. chinensis), both non-irradiated and irradiated. The ESR signal s of irradiated chunggyungchae decreased over a longer storage time, howeve r, even after 6 months of ambient storage, these signals were still disting uishable from those of non-irradiated samples. The most successful estimate s of absorbed dose (5 and 8 kGy) were obtained immediately after irradiatio n using a quadratic fit with average values of 4.85 and 8.65 kGy being calc ulated. (C) 2000 Elsevier Science Ltd. All rights reserved.