Comparison Between Sensory and Nephelometric Evaluations of Tannin Fractions Obtained by Ultrafiltration of Red Wines

Abstract

Introduction: Although the assessment of red wine quality relies primarily on a sensory description of tannins, it may be usefully completed by some knowledge of the physicochemical properties of these tannins. The present study has a double aim: (1) to gain insight into the sensory properties of subpopulations of proanthocyanidic tannins of different molecular sizes (obtained through several ultrafiltration steps), as well as into the kinetics of the haze formed by these fractions when reacted with polyvinylpyrrolidone (as measured by nephelometry) and (2) to determine whether a correlation exists between the sensory and the nephelometric data. Materials and Methods To this end, two wines from different grape varieties were sequentially ultrafiltered to provide three tannic fractions which differed by the range of their polymerization degrees. Then, these fractions were added (individually or in combination) into their native wine matrix (previously deprived of all its polyphenols via charcoal treatment) according to a specific experimental design. These reconstituted wines were characterized by nephelometry and by a static (quantitative descriptive analysis) and a dynamic (temporal dominance of sensations) sensory method. Results and Discussion: Wines containing the largest size tannins (highest range of polymerization degrees) were perceived as more astringent and cause drying in the mouth and after spitting. Concerning the temporality of perception, wines containing the fraction with the largest tannins provide long inmouth drying, and the astringency and in-mouth drying perceptions were the most persistent features. Conclusion: Finally, a highly positive correlation between nephelometric and quantitative descriptive analysis data was shown

Polyphenolic profile and stilbene content of Albanian “Kallmet” monovarietal wine

“…Wine tannins consist essentially of proanthocyanidins (condensed tannins) made by polymerization of 3flavanyl monomers (catechins and gallocatechins, epicatechins and epigallocatechins and their galloylated forms) in which two main classes are procyanidins and prodelphinidins (Porter et al, 1985). It was found that they are the major contributors to the body and mouth feel (astringency) of wine (Rébénaque et al, 2015), as well as color stabilizers of wine by forming long-lived polymeric complexes with anthocyanins (Ribéreau-Gayon et al, 2006).…”

Salivary Protein-Tannin Interaction: The Binding behind Astringency

“…Based on polyphenol/mucin reactivity, a micro-plate assay was also developed [151]. Tannic acid [150], grape seed extracts [151], wine extracts [63], tannin fractions added to model solutions [152] were analysed by nephelometry. The turbidity of the solution, formed by the tannin-protein aggregates, linearly correlated with astringency.…”