Nutritional quality, volatile organic compounds and element compositions of indigenous upland rice

Abstract

Rice (Oryza sativum L.) is important staple food to ensure food security for many people specially in Asia. This study aimed to investigate grain nutrition, proximate composition, and organic volatile compounds (VOCs) and mineral contents of rice varieties. Significant differences in the content of nutritional compositions and VOCs were observed. Thirty-eight VOCs were the main aroma contributors. Principal Component Analysis (PCA) of VOCs explained 55.2 % of the total variation, which could effectively separate volatile compounds. The variable influence on projections (VIPs) in the Partial Least-Squares Discriminant Analysis (PLS-DA) model identified 2-hexanol, (Z-Z)-3,6-nonadienal and (Z)-2-octenal as aroma biomarkers. The detection limit of 10 selected element ranged between 0.00039 – 0.00654 µg/g, and the limit of quantification varied from 0.00179 to 0.01984 µg/g, the linear correlation coefficient was greater or equal to 0.9948 (R² ≥ 0. 9948). In addition, Magnesium (Mg) was the predominant elements in the upland rice samples. The content of Mg ranged between 107.93 µg/g and 446.68 µg/g. The PCA on element contents represented 95.3 % of the total variation. The VIPs in the PLS-DA model identified Mg, Iron (Fe) and Calcium (Ca) as a biomarker. The variation in the characteristic VOCs and elements in rice varieties, providing a theoretical basis for identifying a significant VOCs and elements in rice variety.