Supramolecular approaches to the study of the astringency elicited by wine phenolic compounds

Abstract

The objective of this study is to review the scientific evidences and to advance into the knowledge of the molecular mechanisms of astringency. Astringency has been described as the drying, roughing and puckering sensation perceived when some food and beverages are tasted (1). The main, but possibly not the only, mechanism for the astringency is the precipitation of salivary proteins (2,3). Between phenolic compounds found in red wines, flavan-3-ols are the group usually related to the development of this sensation. Other compounds, phenolic or not, like anthocyanins, polysaccharides and mannoproteins could act modifying or modulating astringency perception by hindering the interaction between flavanols and salivary proteins either because of their interaction with the flavanols or because of their interaction with the salivary proteins. Furthermore, the possible existence of synergism on astringency between phenolic substances (4) has recently arisen. Salivary proteins have been grouped in six main classes: histatins, statherin, cystatins, and proline-rich proteins (acidic, basic and glycosylated) (5). The possible existence of selective interactions between different types of wine phenolic compounds and different salivary protein classes could be responsible for the observed synergisms. To obtain further insights into the interactions between these compounds and salivary proteins that could explain the synergistic effect observed, we have studied the interactions between flavanols and salivary proteins by quenching of fluorescence and HPLC-DAD. Quenching constants calculated and chromatographic profiles obtained could partially explain the synergisms observed in the sensory evaluation of wine phenolic compounds. Furthermore, the effect of the presence of other molecular species, in particular anthocyanins, in the interactions between flavanols and salivary proteins has also been studied. Results obtained confirm the existence of interactions between anthocyanins and salivary proteins which could hinder the interaction between flavanols and salivary proteins, affecting the perceived astringency.

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