Electron paramagnetic resonance study of some varieties of gamma-irradiated soybean

Electron paramagnetic resonance (EPR) spectroscopy was used to investigate free radicals formed in gamma irradiated Brazilian soybean (Glycine max) cultivars. The beans were irradiated by a 60Co source with doses ranging from 1 to 15 kGy. Before irradiation, the representative soybean EPR spectrum is composed of a sextet centered at g=2.0 and a sharp singlet at the same g-value. The stability of the EPR signal of 10 kGy-irradiated samples was followed for over 7 months after irradiation. The results were compared with non-irradiated samples and showed a good possibility of detection of previous radiation treatment for higher doses. It was also analyzed the contribution to the EPR signal of different parts of the bean showing a prominent signal coming from the hilum.