Molecular mechanisms of whey protein in inhibiting oral pungency perception: insights from sensory evaluation,...

Capsaicin (CAP) is widely valued for its ability to enhance flavor, yet its pungency can cause discomfort in sensitive individuals. Although milk is recognized as an effective remedy to inhibit this sensation, the specific functional components and underlying mechanisms remain to be fully elucidated. Because whey protein is a major bioactive constituent of milk, it is hypothesized to play a key role in this process. This study investigates the molecular mechanisms by which whey protein inhibits oral pungency perception, employing an integrated methodology. This includes sensory evaluation, molecular docking, molecular dynamics simulations, and multispectral analytical techniques.

Sensory evaluation revealed that skim lactose-free milk containing whey protein reduced CAP-induced pungency by up to 23.39%, demonstrating a clear dose-dependent relationship. Molecular docking and dynamics simulations indicated that CAP binds stably within the hydrophobic cavity of β-lactoglobulin, primarily through hydrogen bonding and hydrophobic interactions, with ARG-148 identified as a critical residue. The resulting CAP-β-lactoglobulin complex exhibited greater stability than the CAP-transient receptor potential vanilloid 1 (TRPV1) complex. UV-visible spectroscopy showed a redshift in the absorption peak of the protein from 274.9 nm to 275.8 nm upon CAP addition to a 97.1 g kg^-1 whey protein solution. Fluorescence spectroscopy confirmed a slight blue shift in the emission peak of whey protein upon CAP binding, indicating an increase in the hydrophobicity of the microenvironment.

These findings demonstrate that whey protein suppresses pungency perception by competitively binding to CAP and inhibiting TRPV1-mediated signal transduction. This study provides a theoretical basis for the development of functional beverages designed to inhibit pungency. © 2026 Society of Chemical Industry.