EPR investigations of gamma-irradiated ground black pepper

The γ-radiation treatment of ground black pepper samples resulted in the production of three paramagnetic species (GI–GIII) which arise from a different origin and have different thermal behavior and stability. The axially symmetric spectra can be characterized by the spin Hamiltonian parameters: GI (g⊥=2.0060g⊥=2.0060, g∥=2.0032g∥=2.0032; A⊥=0.85mT, A∥=0.70mT) and GII (g⊥=2.0060g⊥=2.0060, g∥=2.0050g∥=2.0050; A⊥=0.50mT, A∥=0.40mT) assigned to carbohydrate radical structures. The parameters of EPR signal GIII (g⊥=2.0029g⊥=2.0029, g∥=2.0014g∥=2.0014; A⊥=3.00mT, A∥=1.80mT) possessed features characteristic of cellulose radical species. The activation energies, evaluated by Arrhenius analysis, are in order Ea(GI)