Analysis of irradiated jujube (Zizyphus jujuba) by photostimulated luminescence and electron spin resonance spectroscopy

Possibility of photostimulated luminescence (PSL) and electron spin resonance (ESR) to detect γ-irradiation of jujube (Zizyphus jujuba) was investigated. The jujube samples were exposed to γ-irradiation at doses of 1, 3, 5, and 10 kGy. The PSL results showed that jujube exposed to at 1 kGy or more had a photon count of greater than 5,000 count/60 sec (positive), while the non-irradiated jujube yielded a photon count of less than 700 photon count/60 sec (negative). However, physical parameters (light exposure, storage, and thermal treatment) of irradiated jujube samples gave a strong effect on the PSL signal, resulting in decrease of the photon counts from the initial counts. ESR spectroscopy analysis of irradiated jujube revealed specific signals derived from cellulose radicals, and irradiation caused a significant increase in the ESR signal intensity of the jujube samples without any changes in the spectral patterns. Light exposure, storage, and thermal treatment of jujube resulted in significant decreases in the ESR signal intensities of cellulose radicals.