Insights into the mechanism of flavor compound changes in strong flavor baijiu during storage by using the density functional theory and molecular dynamics simulation

[Display omitted] •Ester alkyl-oxygen protonation has lower Ea than acid hydroxyl-oxygen protonation.•DFT results explained why acids increased and esters decreased during SFB storage.•Electrostatic interaction was a major contributor to the flavor compound changes.•Ethanol–water system containing acids had more H-bonds than that containing esters.•MD simulation results proved that the acids can strengthen associative structures. The aging procedure/storage is essential to enhance the organoleptic quality of strong flavor baijiu (SFB). How the storage affects flavor changes in SFB, that is, the aging mechanisms remains unclear. Herein, the physical and chemical effects on the main flavor compounds of SFB during storage were investigated using the density functional theory (DFT) and molecular dynamics (MD) simulation. DFT calculation results showed that the activation energy of ester alkyl-oxygen protonation was lower than that of acid hydroxyl-oxygen protonation, which explained the reason why the concentrations of acids increased and those of esters decreased during SFB storage. MD simulation results showed that electrostatic interaction was a major contributor to SFB and that the ethanol–water system containing acids had a stronger electrostatic energy and more hydrogen bonds than the ethanol–water system containing esters. These findings revealed that acids are prone to generating and strengthening associative structures in SFB during storage.