Enhancing the flavor quality of Penthorum chinense Pursh through Aspergillus fermentation

This study systematically investigated the effects of solid-state fermentation by three fungal strains across different periods on Penthorum chinense leaves, aiming to improve flavor quality while preserving good bioactivity. Among strains, A. cristatus fermented for 9 days best retained total polyphenols and flavonoids, effectively degraded tannins, achieved peak antioxidant and alcohol dehydrogenase (ADH) activation activities, and was identified as the optimal sample by principal component analysis (PCA). Mechanistically, 9-day A. cristatus fermentation significantly optimized the free amino acid profile, increasing umami (aspartic acid, alanine), sweet-tasting amino acids, and γ-aminobutyric acid, while reducing bitter amino acids. Non-targeted metabolomics revealed 756 metabolites, particularly benzenoids and phenylpropanoids. Volatile profiling further showed marked changes in alcohols, esters, and terpenoids, consistent with a shift toward a more fruity and sweet aroma-related chemical profile. In conclusion, A. cristatus fermentation simultaneously enhances the flavor quality and bioactivity of P. chinense through biotransformation.