Concentration-dependent modulation of the aroma profile of Jiang-flavor Baijiu by isoamyl alcohol through noncovalent interactions with key aroma compounds.

Isoamyl alcohol (IAA), a key higher alcohol in Baijiu, is capable of both enhancing and disrupting aroma balance depending on its concentration. This study investigates its concentration-dependent role using recombination models with quantitative descriptive analysis, molecular dynamics simulations and 1H NMR spectroscopy. At 200-400 mg/L, IAA enhanced floral and fruity aromas while suppressing acidic and roasted aroma, consistent with reduced compound volatility. Above 600 mg/L, the inhibitory effect on aroma release weakened. These concentration-dependent effects on aroma are driven by changes in compound volatility mediated by hydrogen bond, with van der Waals and Coulomb interactions contributing. 1H NMR confirmed hydrogen bonding between IAA and aroma compounds via 0.05-0.09 ppm downfield shifts. Notably, the 400-650 mg/L range represents a pivotal transition window for sensory traits, compound volatility and hydrogen bond formation with IAA. However, a limitation remains in fully bridging the nonlinear gap between microscopic molecular interactions and human olfactory perception, as in vivo sensory integration involves complex perceptual mechanisms beyond physical volatility modulation.