Insights into the potential metabolic basis of flavor formation during fermentation of black truffle (Tuber indicum) extract: combining sensory evaluation with metabolomics.

To improve flavor profile of lower-grade Chinese black truffle, a method combining water extraction and fermentation was developed. Sensory evaluation, volatile and non-volatile metabolomics were employed to trace the dynamic changes of aroma, VOCs, and non-volatile metabolites during fermentation. The fermentation process shifted the sensory profile from earthy/leather-like characteristics toward more pleasant buttery, fruity, and fermentation-related notes. Day 6 represented the most fermentation stage observed under the experimental conditions, where the content of VOCs also reached the peak. Odor activity value (OAV) analysis identified 24 key aroma compounds, predominantly alcohols and esters, including phenethyl alcohol. KEGG pathway enrichment analysis indicated that flavor formation was primarily driven by alanine, aspartate, and glutamate metabolism, valine, leucine and isoleucine biosynthesis, and the TCA cycle. These findings elucidate the potential metabolic basis underlying aroma development in fermented truffle products, providing a theoretical basis for producing high-value seasonings.