Odor threshold dynamics during Baijiu aging: Ester–acid interactions

This study aims to investigate the influence of the interactions between the major aromatic compounds in Baijiu (esters and acids) on the aroma and taste profile of Baijiu. The electronic nose and electronic tongue were used to assess the effects of adding acids on the aroma and taste of Baijiu. Results indicate that the incorporation of acids remarkably alters the olfactory intensity of Baijiu, with minimal impact on its taste, thereby confirming the profound influence of ester–acid interactions on volatile aroma components. Furthermore, the best-estimated threshold method was utilized to determine the aroma thresholds of four key esters and their corresponding acids. Butyric, hexanoic, and lactic acids exhibit synergistic effects by substantially lowering the aroma thresholds of their respective esters. By contrast, acetic acid exerts a masking effect, thereby elevating the aroma threshold of ethyl acetate. Sensory evaluation corroborated the influence of ester–acid interactions on the overall aroma of Baijiu, which is consistent with the aroma threshold findings. Molecular docking methods were applied to decipher the mechanism underlying ester–acid interactions. Hydrogen bonding emerges as a pivotal interaction mode among aromatic compounds, with the binding energy intimately linked to the extent of synergy or masking effects. • The ester-acid interactions have a powerful influence on odor threshold. • Hexanoic acid decreases the odor thresholds of ethyl lactate. • Acetic acid increases the odor threshold of ethyl acetate. • Explaining how the “acid increase and ester decrease” affects Baijiu's flavor.