Identification of irradiation treatment in black pepper by electron paramagnetic resonance

Electron paramagnetic resonance spectroscopy was applied to study free radicals in black pepper, and to evaluate the potential of these radicals in identifying radiation treatment. A doublet signal was detected at g = 2.0042 and a = 1.83 mT, produced exclusively by radiolysis. This signal is as stable as that of irradiated cellulose, and can be used to identify recent radiation treatment. A line produced both by radiolysis and thermolysis was observed, and its behaviour with thermal treatments suggests that it cannot be used as an irradiation indicator for doses up to 30 kGy, contradicting a model proposed in the literature.