EPR study of gamma – irradiated cereal foods

The results from the EPR studies on wheat and oat bran, rolled oats, buckwheat and different kind of rice – white, brown and parboiled rice before and after gamma-irradiation are reported. Before irradiation all samples exhibit one weak singlet EPR line characterized with common g-factor of 2.00480.0005 and six lines due to Mn naturally available in the plants. Only parboiled rice did not show any EPR spectrum before irradiation. After irradiation, in addition of the Mn signal a typical “cellulose-like” triplet EPR spectrum appears, attributed to cellulose free radicals, generated by gamma-irradiation. This EPR spectrum is superimposed by a partly resolved “carbohydrate” spectrum, which however is the main spectrum for parboiled rice samples. The fading kinetics of radiation-induced EPR signals were studied for a period of 90 days after irradiation. The reported results unambiguously show that the presence of characteristic EPR spectra of cereal samples can be used for identification of previous radiation processing.