Identification of X-ray irradiated walnuts by ESR spectroscopy.

Abstract Samples of non-irradiated walnuts exhibit a single line with a g value of 2.0045 ± 0.0006. The irradiation process gives rise to “cellulose-like” Electron Spin Resonance (ESR) spectrum two lines symmetrical to the central line, at a distance of ca. 3 mT. Irradiation increases the central line and produces two satellite peaks (lines) with an amplitude growing with dose. The stability of the radiation-induced ESR signal at room temperature was studied from a quantitative point of view. The fading study and dose evaluation were pursued for a period of two years analyzing irradiated walnuts samples. The reported curves, describing the fading at different doses, differ only by a multiplicative factor and the attenuation factor (the ratio between the amplitude measured and the amplitude evaluated after irradiation) depends only on the time elapsed following treatment. Highlights • A method to detect irradiation treatment in walnuts was optimized. • The stability of the ESR signal over a period of two years was studied. • Parameters describing the fading effects were evaluated. [ABSTRACT FROM AUTHOR]