Astringency and Lubrication of Polyphenol Systems under Dynamic Salivary Replenishment.

Polyphenol-saliva interactions disrupt mucin-mediated lubrication and induce astringency, yet most models neglect dynamic salivary replenishment. Here, a stepwise artificial saliva (AS) addition model was developed to compare tannic acid (TA) and (-)-epigallocatechin gallate (EGCG), with or without xanthan gum (XG). Four systems (TA-AS, EGCG-AS, TA-XG-AS, EGCG-XG-AS) underwent sequential AS replenishment and were characterized using colloidal, spectroscopic, tribological, and electronic tongue analyses. TA-AS progressively formed larger aggregates and exhibited the highest friction, whereas EGCG-AS generated smaller particles and showed lower friction at intermediate stages. In XG-containing systems, TA-XG-AS formed ternary networks with mucin, stabilizing lubrication and reducing astringency. EGCG-XG-AS primarily enhanced film retention with limited aggregation. Spectroscopy and molecular docking suggested stronger TA-mucin interactions, whereas EGCG interactions were more reversible. Overall, polyphenol structure and XG modulation under dynamic replenishment governed mucin lubrication and astringency attenuation.