Flavor enhancement of Grifola frondosa extracts via enzymatic hydrolysis and subsequent Maillard reaction treatment: Volatile compounds and key odorants identification.

Grifola frondosa (G. frondosa) is a highly valued edible fungus, yet systematic studies on its processing and flavor characteristics remain limited. This study aimed to investigate the optimal conditions for the Maillard reaction of G. frondosa enzymatic hydrolysates (GEH) under different amino acid, reducing sugar and reaction conditions, as well as the changes in volatile flavor compounds (VFCs) of G. frondosa extract (GE), GEH and the Maillard reaction products (MRPs). Bromelain was identified as the most suitable protease, as it yielded the highest peptide content and degree of hydrolysis. In addition, its cleavage-site matching pattern and greater potential to generate highly reactive ε-amino groups further demonstrated its superiority in producing Maillard reaction precursors. Sensory evaluation demonstrated that the MRPs of the enzymatic hydrolysate prepared with 3% xylose and 5% glycine (120 °C for 20 min, pH 8) exhibited the highest overall acceptability. Gas Chromatography-Ion Mobility Spectrometry and relative odor-active values analysis revealed that GE was dominated by mushroom-like C8 compounds (e.g., 1-octen-3-ol and 1-octen-3-one), whereas GEH was rich in ketones derived from fatty acid degradation (e.g., hexan-2-one and pentan-2-one) and MRPs were abundant in esters and aldehydes (e.g., ethyl butanoate and 3-methylbutanal) generated via the Maillard reaction. During the process from GE to GEH and then to MRPs, the content of C8 compounds decreases, short-chain ketones first increase and then decrease, while aldehydes, esters, and pyrazines gradually increase. This study provides a more integrated understanding of how precursor changes translate into volatile formation and sensory evolution.