Volatile Chemistry and Aroma Differences in Commercial Soy Sauces: Sensory Links and Odorant-Receptor Interactions

Volatile and sensory differences among 28 commercial soy sauces were investigated using HS-GC-IMS, check-all-that-apply (CATA) evaluation, aroma addition experiments, and molecular docking. Ninety-nine volatile compounds from 14 chemical classes were detected. Total semiquantitative volatile concentrations ranged from 2024.56 to 6279.59 μg/mL, with esters, alcohols, and aldehydes accounting for 70.68% of the total. Of the 24 CATA descriptors, 13 were retained for product-level correlation analysis. Exploratory Pearson analysis indicated that alcoholic, savory, and malty attributes were associated with a group dominated by fatty acids, branched-chain alcohols, and esters, whereas woody and chocolate-like attributes showed an opposing pattern involving several aldehydes, ketones, and alkylpyrazines. Fifteen candidate compounds were evaluated by single-compound addition. Benzaldehyde and ethyl propanoate enhanced savory perception; 2-ethyl-3,5-dimethylpyrazine enhanced the alcoholic attribute; methyl 2-methylbutyrate enhanced smoky, meaty, and alcoholic attributes; and ethyl acetate enhanced malty, meaty, and alcoholic attributes. Several other additions produced opposing or nonsignificant effects, indicating matrix- and concentration-dependent responses. Among the binary docking models, guaiacol-2-ethyl-3,5-dimethylpyrazine and homofuraneol-benzaldehyde produced the lowest scores with OR10G4 (-10.10 kcal/mol) and OR5M3 (-13.32 kcal/mol), respectively. In combination, these results show that product-level correlations can guide candidate selection but require matrix-based sensory verification, while docking provides structural hypotheses for odorant co-binding.