Investigation of radical locations in various sesame seeds by CW EPR and 9-GHz EPR imaging

Abstract

We investigated the location of radical in various sesame seeds using continuous-wave (CW) electron paramagnetic resonance (EPR) and 9-GHz EPR imaging. CW EPR detected persistent radicals (single line) for various sesame seeds. The EPR linewidth of black sesame seeds was narrower than that of the irradiated white sesame seeds. A very small signal was detected for the white sesame seeds. Two-dimensional (2D) imaging using a 9-GHz EPR imager showed that radical locations vary for various sesame seeds. The paramagnetic species in black sesame seeds were located on the seed coat (skin) and in the hilum region. The signal with the highest intensity was obtained from the hilum part. A very low-intensity image was observed for the white sesame seeds. In addition, the 2D imaging of the irradiated white sesame seeds showed that free radicals were located throughout the entire seed. For the first time, CW EPR and 9-GHz EPR imaging showed the exact location of radical species in various sesame seeds.

Keywords::

• EPR
• imaging
• sesame
• antioxidant
• free radicals
• food
• irradiation

Acknowledgements

Part of this research was supported by a Grant-in-Aid for Exploratory Research (24650247) and for Scientific Research (B) (25282124) from the Japan Society for the Promotion of Science (JSPS) (K.N.).

Declaration of interest

The authors report no declarations of interest. The authors are responsible for the content and writing of the paper.