Investigation on the dynamic change of key odor compounds, free amino acids and chroma during soy sauce fermentation

Odor-active compounds in high-salt liquid-state fermentation soy sauce (HLFSS) during fermentation from 30 to 230 days were characterized using molecular sensory science. Sensory evaluations revealed significant variations in green bean, roasted potato, caramel and smoky odor attributes; HLFSS at 180 days exhibited optimal color depth. Forty-three common volatile compounds were identified via SE-SAFE-GC-MS, of which 37 odorants were odor-active. Quantitative analysis combining OAV determined 17 key odorants. Free amino acid analysis revealed that the metabolism of glutamic acid and aromatic amino acids significantly affected the accumulation of flavor compounds. The rapid depletion of arginine and histidine was associated with the HLFSS flavor improvement. PCA and OPLS-DA further revealed the fermentation process could be divided into substrate decomposition stage (30-60 days), odorant synthesis stage (90-150 days), and flavor maturation stage (180-230 days). This study provides a theoretical basis for the directional regulation of HLFSS flavor and process optimization.