Mechanistic insights into taste modulation of Xanthoceras sorbifolium leaf tea fermented by Aspergillus cristatus and Aspergillus neoniger: an integrated component–taste relationship analysis

Xanthoceras sorbifolium leaf tea has notable pharmacological potential, but its taste limits broader acceptance. In this study, the tea was fermented with Aspergillus cristatus (AC) or Aspergillus neoniger (AN), and taste modulation was investigated by electronic tongue analysis and untargeted metabolomics. AC fermentation increased bitterness and sweetness but reduced umami and saltiness, whereas AN increased sourness and reduced saltiness and bitterness. Integrated metabolite–taste analysis identified 34 and 48 key differential metabolites in AC- and AN-fermented teas, respectively. Redundancy analysis highlighted flavonoids, amino acids, triterpenoid saponins, and glycosides as major contributors. Time-series clustering revealed their dynamic changes during fermentation. Molecular docking indicated favorable metabolite–receptor interactions, and microscale thermophoresis further validated the binding affinities of key metabolites to corresponding taste receptors. These findings explain the metabolic basis of fermentation-driven taste modulation and support targeted microbial processing to improve fermented herbal tea quality.