Colloidal stability of tannins: astringency, wine tasting and beyond

TL;DR

This paper investigates the colloidal stability of tannins in wine-like solutions, focusing on tannin-tannin and tannin-protein interactions, to better understand their roles in wine tasting and astringency.

Contribution

It provides a detailed analysis of tannin interactions and introduces a quantitative framework for understanding tannin-induced protein aggregation relevant to astringency.

Findings

Constructed a precipitation map for tannin-tannin interactions.

Quantified tannin-assisted micellization of salivary proteins.

Linked colloidal phenomena to sensory properties in wine tasting.

Abstract

Tannin-tannin and tannin-protein interactions in water-ethanol solvent mixtures are studied in the context of red wine tasting. While tannin self-aggregation is relevant for visual aspect of wine tasting (limpidity and related colloidal phenomena), tannin affinities for salivary proline-rich proteins is fundamental for a wide spectrum of organoleptic properties related to astringency. Tannin-tannin interactions are analyzed in water-ethanol wine-like solvents and the precipitation map is constructed for a typical grape tannin. The interaction between tannins and human salivary proline-rich proteins (PRP) are investigated in the framework of the shell model for micellization, known for describing tannin-induced aggregation of beta-casein. Tannin-assisted micellization and compaction of proteins observed by SAXS are described quantitatively and discussed in the case of astringency.