Identification of potential flavonoids strongly correlated with bitterness and astringency in quinoa seedling vegetables via metabolomics and electronic tongue

Quinoa ( Chenopodium quinoa Willd.) seedlings are nutrient-dense leafy vegetables, but their inherent bitterness and astringency limit consumer acceptance. The chemical basis underlying these sensory attributes remains largely unclear. In this study, four quinoa seedling varieties differing in seed coat colour were evaluated using electronic tongue analysis in combination with comprehensive metabolomics. Among the detected flavor attributes, bitterness and astringency were the most prominent in the four identified quinoa seedling varieties. Meanwhile, 2060 metabolites were identified across the four varieties, with differential metabolites predominantly enriched in flavonoids. Correlation analysis revealed significant associations between flavonoids and bitter, astringent sensory traits of quinoa seedlings vegetables, indicating a potential connection to unpleasant taste perception. Among these flavonoids, quercetin and kaempferol glycoside derivatives showed the strongest correlation with bitter and astringent sensory attributes. This study deepens our knowledge of flavor-related metabolites and offers correlational references for breeding low-bitterness quinoa varieties.