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Mechanisms of astringency: Structural alteration of the oral mucosal pellicle by dietary tannins and protective effect of bPRPs

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International audience; The interaction of tannins with salivary proteins is involved in astringency. This paper focussed on saliva liningoral mucosae, the mucosal pellicle. Using a cell-based model, the impact of two dietary tannins (EgC and EgCG)on the mucosal pellicle structure and properties was investigated by microscopic techniques. The role of basicProline-Rich-Proteins (bPRPs) in protecting the mucosal pellicle was also evaluated.At low (0.05 mM) tannin concentration, below the sensory detection threshold, the distribution of salivarymucins MUC5B on cells remained unaffected. At 0.5 and 1 mM, MUC5B-tannin aggregates were observed andtheir size increased with tannin concentration and with galloylation. In addition, 3mM EgCG resulted in higherfriction forces measured by AFM. In presence of bPRPs, the size distribution of aggregates was greatly modifiedand tended to resemble that of the “no tannin” condition, highlighting that bPRPs have a protective effectagainst the structural alteration induced by dietary tannins.