A study on volatile metabolites screening by HS-SPME-GC-MS and HS-GC-IMS for discrimination and characterization of white and yellowed rice

Background and objectives: Yellowed rice results in serious economic losses to grain industry. This study attempted to profile the volatile metabolites in before- and after-yellowing rice of five Chinese common rice cultivars. Application untargeted metabolomics approach to discover the biomarkers in yellowed rice.
Findings: The volatile metabolites were detected by headspace-gas chromatography–ion mobility spectrometry (HS-GC-IMS) and headspace solid-phase microextraction–gas chromatography-mass spectrometry (HS-SPME-GC-MS). Yellowed rice emitted more aldehydes, alcohols, furan, and less ester than white rice. Partial least squares-discriminant analysis (PLS-DA) based on GC-MS and GC-IMS data was revealed a good classifying tool for white and yellowed rice. Hexanal, nonanal, octanal, 1-pentanol, and 2-pentyl-furan were selected as the potential markers by the variable importance in projection (VIP) variable selection method. All of these markers were associated with fatty acid oxygenation.
Conclusions: Comparative analysis and biomarker identification of the volatile metabolites of different cultivars of Chinese yellowed rice lay a foundation for research on yellowing mechanism.
Significance and novelty: The results of the current study provide a useful basis in the rice yellowing mechanism study. Additionally, a rapid rice aroma analysis method using GC-IMS was developed. So in the future, yellowed rapid reorganization GC-IMS technology could be a preferred choice.