Perceived astringency in wine: a predictive model

Sensations perceived in the act of tasting are important determinants of consumer response to red wine. Astringency is a tactile stimulus that strongly influences wine acceptability. Astringency descriptors account for more than a half of the total terms in the mouth-feel wheel proposed for describing the sensory properties of red wine. The physiological mechanism of the astringency perception in wine is based on the reaction of phenolic compounds with salivary proteins and the consequent formation of insoluble astringent/protein complexes. The availability of in vitro assays to estimate the strength of the sensation induced by different phenolic compounds became crucial in order to optimise the processing conditions in relation to this important driver of wine acceptability and sensory quality. In this work recent advancements in predicting astringency induced by phenolic compounds are discussed and new and promising methods are presented. Critical points in collecting both sensory and chemical data are reviewed. In particular, the application of the "Astringency Mucin Index" (AMI) in predicting the astringency induced by grape and wine phenol extracts is shown. The results of the use of the AMI on commercial phenolic extract, seed phenolic extracts from 'Aglianico' grape, 18 'Sangiovese' experimental wines and 20 commercial 'Aglianico del Vulture' wines are presented. Future developments of methods capable of predicting astringency are discussed.