NMR-based metabolic profiling discriminates the geographical origin of raw sesame seeds

Abstract

Sesame seeds are an oil crop mainly cultivated in Asian and African countries. Identification of the geographical origin of sesame seeds is an important issue for preventing adulteration and for quality assurance. This study was performed to establish a discrimination model and investigate potential biomarkers for differentiating the geographical origin of sesame seeds from Korea, China, and other countries (India, Nigeria, and Ethiopia) by nuclear magnetic resonance -spectroscopy based metabolic profiling. A total of 24 polar metabolites in sesame seeds from 10, 6, and 4 samples of Korea, China, and other countries, respectively, were identified, and an orthogonal partial least squares-discriminant analysis model was established applying a total normalization and unit variance scaling method. Leave-one-out cross validation showed an accuracy of 97.5, 90.0, and 100.0% in differentiating the sesame seed geographical origin. Acetate, phenylalanine, and tryptophan were suggested as potential biomarkers by variable influence on projection value (over 1.0) and area under the curve value (over 0.75). This study demonstrated that H-1 NMR analysis with multivariate and univariate statistical analyses of the polar metabolites in sesame seeds could be successfully applied to discriminate the geographical origin of sesame seeds. These results could be applied to develop a standard analytical process to verify seed origin and halt the global distribution of falsely labeled sesame seeds.