Molecular basis for the divergence in aroma profiles between traditional and modern industrial soy sauce by quantitative metabolomics and sensory reconstitution.

Chinese traditional-fermented soy sauce (TSS), crafted through thin-layer koji-making and prolonged moromi fermentation, was widely regarded as having superior flavor compared to modern industrial fermented soy sauce (MSS), despite its lower efficiency. However, the objective difference remained unclear. This study systematically compared the aroma profiles of commercial TSS and MSS. Sensory results revealed that TSS exhibited greater intensity in smoky, sour, malty, cooked potato and roasted nut attributes, while MSS was characterized by pronounced caramel-like, floral and fruity aromas. To analyze the basis of differences, 57 differential compounds were obtained from 140 compounds detected based on p and fold change (FC), 27 of which were higher in TSS and 30 higher in MSS. Further, screening by odor activity value (OAV), 24 compounds were identified as key markers, containing 9 higher in TSS and 15 higher in MSS. This study could provide theoretical value for the quality improvement of soy sauce.