Detection of irradiated frog (Limnonectes macrodon) leg bones by multifrequency EPR spectroscopy

• Published in: Food chemistry 2012-12, Vol.135 (4), p.2313-2319
• Main Authors: Bercu, V., Negut, C.D., Duliu, O.G.
• Format: Article
• Language: English
• Subjects: Animals; Anura; Arrhenius plot; Biological and medical sciences; Electron Spin Resonance Spectroscopy - methods; EPR spectroscopy; Food engineering; Food industries; Free radical kinetics; Frog leg bones; Fundamental and applied biological sciences. Psychology; Gamma irradiation; Gamma Rays; General aspects; Leg Bones - growth & development; Leg Bones - radiation effects; Limnonectes; Macrodon; Methods of analysis, processing and quality control, regulation, standards; Ranidae - growth & development
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2012.07.015

► Gamma ray sterilization of foodstuff induces free radicals whose presence is evidence by EPR spectroscopy. ► X and Q bands EPR spectroscopy in combination with thermal treatments allow a better identification of free radicals. ► Experimentally determined activation energy and time stability of induced free radicals. ► Significantly thermolabile free radicals with respect to mammal bone tissue. The free radicals of irradiated frog Limnonectes macrodon leg bones tissue were studied by electron paramagnetic resonance in both X and Q bands. The kinetic behaviour, the activation energy as well as the thermal stability of the radiation-induced radicals in bone tissue were investigated by means of both isothermal and isochronal annealing. Unirradiated bone tissue displayed the presence of Mn2+ ions at both frequencies, while a week EPR singlet was evidenced only at 34GHz. When irradiated with 60Co gamma ray, the EPR spectra completely changed their patterns and intensity, the overall spectra provin, at both frequencies, to be typical axial ones. The 100°C isothermal annealing studies attested the existence of two different free radical species, significantly more labile than in the case of mammal bone tissues. At the same time, the Arrhenius plot of 15kGy irradiated bones evidenced two different kinetic regimes with two different activation energies.