Red wine astringency: correlations between chemical and sensory features

Abstract

Astringency is a crucial sensory attribute typically described as the drying and/or puckering sensation occurring after the consumption of tannin-rich foods and beverages. In this study, thirty-seven red wines from different varieties, origins and styles were evaluated, analyzing both chemical and sensory features. Principal Component Analysis was used for dimensionality-reduction and for correlating selected chemical parameters against astringency. The results showed that tannin content was the most important chemical parameter influencing overall astringency but more clearly the dryness sub-quality, followed by pH, titratable acidity and alcohol content. A further evaluation compared the performance of two widely employed methods for tannin determination (i.e., methylcellulose and Harbertson-Adams assays), as predictors of wine astringency, showing differences as astringency estimators; with lower variability of HA in the low and mid tannin concentration range and MCP at high tannin concentrations. Interestingly, the fitted curve for HA vs. astringency exhibited a sigmoidal behavior, where diversion from linearity might be due to a protein precipitation threshold, as well as a maximum tannin concentration beyond which sensorial saturation may be reached.