EPR-Investigation of Irradiated Imported Foodstuffs and Parameters of EPR Signals

Study by EPR (electron paramagnetic resonance) technique of a wide range of food products imported to Kazakhstan and of analogous domestic foodstuffs has been carried out in order to develop a methodic that would make it possible to control the fact of radiation sterilization of food. Elaborated method of sample preparing for EPR-study included dividing into components, removing moisture by drying or lyophilizing then grinding till dimensional work fraction. Selection of optimal conditions for spectra recording and algorithm of spectra treatment enabled authors to allocate correctly initial EPR-signals and to obtain information on shape, intensities and parameters. Model gamma-irradiations of the initial whole products with subsequent study of prepared EPR-specimen have been carried out. Influence of irradiation on the intensities of EPR-signals and possible changes of EPR-characteristics have been studied in dose range (0.1-25) kGy. EPR-signals of free radicals (FR) of radiation origin were obtained from the EPR-spectra of gamma-irradiated delicious fruits, citrus, vegetables and others. Nonmonotonous dependences of FR concentration on a dose, along with linear ones were observed. Intensities of initial signals and of radiation-induced ones are much higher in solid components, than in pulp, dependences on dose are more close to linearity, which can be used in some cases for retrospective EPR-dosimetry. The obtained results can be explained taking into account specificities of the studied objects, and probable impact of radiochemical reactions of the irradiated water products with radicals formed in substances of foodstuff at irradiation.