Electron Spin Resonance Spectroscopy for the Identification of Irradiated Foods with Complex ESR Signals

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Electron Spin Resonance Spectroscopy for the Identification of Irradiated Foods with Complex ESR Signals Jae-Jun Ahn & Kashif Akram & Hyun-Ku Kim & Joong-Ho Kwon

Received: 2 March 2012 / Accepted: 8 May 2012 # Springer Science+Business Media, LLC 2012

Abstract Electron spin resonance (ESR) spectroscopy for the detection of irradiated food could provide complex spectra due to the presence of different nonirradiationspecific paramagnetic species in the sample. Particularly, ESR signals from naturally present Mn2+ could limit the ESR-based detection of irradiated foods of plant origin. In this study, the effects of different concentrations of Mn2+ on the radiation-specific ESR spectral features of radiationinduced crystalline sugar or cellulose radicals were examined. Soy sauce powder with Mn2+ was irradiated at 10 kGy and its effect on the identification of radiation-induced sugar (pak choi, 10 kGy) and cellulose (red pepper powder, 10 kGy) radicals was evaluated. In the blends of red pepper and soy sauce, the left (g1 02.025) and central (g2 02.005) peaks of the cellulose signal significantly decreased with the decline of red pepper content (R2 00.9384, g1; 0.8819, g2). However, the right peak (g3 01.988) significantly increased (R2 00.9353, g3) with an escalation in the soy sauce content. The cellulose radical signals were identifiable from the blends containing more than 50 % red pepper powder. In the blends of soy sauce and pak choi, the ESR intensity of crystalline sugar radicals significantly decreased with the decline in pak choi content (R2 00.9887). However, Mn2+ signal didn’t overlap with the sugar radical signals. The ESR signals from radiation-induced crystalline sugar remained

J.-J. Ahn : K. Akram : J.-H. Kwon (*) Department of Food Science & Technology, Kyungpook National University, Daegu 702-701, Republic of Korea e-mail: [email protected] H.-K. Kim Korea Food Research Institute, Songnam 463-746, Republic of Korea

unaffected; however, the signals from cellulose radicals provided a reduced detectionability depending upon the concentration of Mn2+ in the sample. Keywords Food irradiation . Electron spin resonance . Cellulose radical . Sugar radical . Mn2+ concentration

Introduction Research from the past several decades has offered food irradiation as an effective tool to ensure hygienic quality, enhance shelf life of different products and improve the functional properties of different food ingredients (Diehl 2002; Arvanitoyannis et al. 2009). Due to its enormous positive effects, especially those of a commercial nature, this technology has assumed a significant role in the field of food processing and preservation (Sommers and Fan 2006). Currently different countries have adopted different national regulations regarding irradiated foodstuffs (Arvanitoyannis 2010). Proper labeling is mandatory for the marketing of irradiated food to safeguard the consumer’s right and to create the awareness of this advanced processing technology (Farkas and MohacsiFarkas 2011). The validated detection techniques ar