Revealing the metabolic mechanisms of dried characteristic flavors of Hypsizygus marmoreus based on non-targeted metabolomics and stable isotope tracing technology

Hypsizygus marmoreus develops characteristic dried flavors and enhances its odor expression during the drying process, but the underlying metabolic mechanisms had not been systematically verified. In this study, untargeted metabolomics technology was used to explore the metabolic pathways of key characteristic flavors during drying, combined with stable isotope tracing technology to verify the core role and influencing mechanisms of these pathways. The analysis of key flavor compounds in dried H. marmoreus showed that (E)-2-nonenal, heptanal, (E)-2-octenal, 2-undecanone, 1-octen-3-one, and 2-pentylfuran could all be generated by the oxidation or degradation of linoleic acid. Meanwhile, non-volatile metabolite analysis revealed that 9(S)-HPOD and 13(S)-HPOD, key intermediate products of linoleic acid degradation, were significantly downregulated after drying, and related differential metabolites were significantly enriched in the linoleic acid metabolic pathway ( P = 0.030). It was further confirmed that 13 C 18 -linoleic acid produced 12 volatile compounds through the lipoxygenase pathway. The metabolic mechanism of key characteristic flavor compounds of dried H. marmoreus —including 2-nonenal, 2-octenal, 2-pentylfuran, 1-octen-3-one, and heptanal—was elucidated: these compounds were mainly generated from linoleic acid substrates and catalyzed by lipoxygenase / hydroperoxide lyase via intermediates 9(S)-HPOD, 10(S)-HPOD, and 13(S)-HPOD. These findings provide a theoretical basis for regulating the drying flavor of H. marmoreus . • Dried characteristic flavor compounds of Hypsizygus marmoreus are associated with linoleic acid oxidation and degradation • Non-targeted metabolomics and stable isotope tracing reveal core flavor metabolic mechanisms • Linoleic acid forms dried characteristic flavors via the lipoxygenase / hydroperoxide lyase pathway