A Nuclear Magnetic Resonance Spectroscopy Approach to Discriminate the Geographic Origin of Roasted Asian Sesame Oils

Abstract

The aim of this study was to discriminate the geographic origin of Korean, Chinese, and Indian sesame oils distributed in Korea using H-1 NMR spectroscopy in combination with canonical discriminant analysis (CDA). 1H NMR spectra were obtained from 84 roasted oil samples prepared from 51 Korean, 19 Chinese, and 14 Indian sesame seeds. The integration values of 26 peaks observed in the NMR spectra were determined and normalized on the basis of the peak derived from the terminal CH, of the fatty acids (0.7446-1.0445 ppm). The variables selected for the CDA include the integration value of one peak (2.7208-2.8533 ppm) that signifies the CH2 between two C=C bonds from linoleic acid and the integration values of three peaks (2.9811-3.1151 ppm, 3.5914-3.6819 ppm, and 5.9471-5.9625 ppm) attributed to the protons of sesamolin. The CDA results showed that 80 of the 84 oil samples and five of the six additional commercial sesame oil samples were correctly classified based on their production site. This study demonstrated that H-1 NMR spectroscopy is a useful tool to simultaneously analyze the relative abundance of linoleic acid and sesamolin in the sesame oils and good discrimination between the three Asian sesame oils could be achieved when the 1H NMR analytical data were used in combination with CDA.