Investigation of Different Factors Affecting the Electron Spin Resomance-based Characterization of Gamma-irradiated Fresh, White, and Red Ginseng

Fresh (raw roots), white (dried), and red (steamed-drid) ginseng samples were gamma-irradiated at 0 to 7 kGy. Electron spin resonance (ESR) technique was used to characterize the irradiation status of the samples, targeting the radiation-induced cellulose radicals after different sample pretreatments. All non-irradiated samples exhibited a single central signal (g=2.006), whose intensity showed significant increase upon irradiation. The ESR spectra from the radiation-induced cellulose radicals, with two side peaks (g=2.0201 and g=1.9851) equally spaced (${\pm}3mT$) from the central signal, were also observed in the irradiated samples. The core sample analyzed after alcoholic-extraction produced the best results for irradiated fresh ginseng samples. In the case of irradiated white and red ginseng samples, the central (natural) and radiation-induced (two-side peaks corresponding to cellulose radical) signal intensities showed little improvement on alcoholic-extraction. The water-washing step minimized the effect of $Mn^{2+}$, but reduced the intensity of side peaks making them difficult to indentify. The effect of different origins was negligible, however harvesting year showed a clear effect on radiation-induced ESR signals.