Study of the relationship between red wine colloidal fraction and astringency by asymmetrical flow field-flow fractionation coupled with multi-detection.

Macromolecules including condensed tannins and polysaccharides impact wine taste and especially astringency. Asymmetrical Flow-Field-Flow-Fractionation (AF4) coupled to UV detection (UV), multi-angle light scattering (MALS) and refractive index detection (dRI) has been proposed to separate red wine colloids. The present work aimed at relating AF4-mutidetection profiles with red wine astringency. Fifty commercial red wines characterized by a trained sensory panel were analysed by AF4-UV-MALS-dRI and UV-visible spectroscopy. The analytical data set was built by selecting the three variables most predictive of the astringency score from each table (UV, dRI, MALS, Mw distribution, and UV-visible spectra of whole wine, permeate and retentate A4F fractions) and analysed by principal component analysis. Red wine astringency was more related to variables extracted from the AF4 data than to UV- absorbance of the wine or permeate, confirming the relevance of AF4-multidetection for analysis of the colloidal fraction involved in this perception.

Development of a methodology to study typicity of PDO wines with professionals of the wine sector.

BACKGROUND: Today, many agricultural products claiming a link to their origin and typicity receive a warm welcome on the market. Nevertheless, the notion of typicity is blurred for consumers and needs to be objectified for communication purposes. This study aims at formalizing a methodology for studying typicity of terroirs, with PDO wines as an example, using a participatory approach with professionals of the wine sector from terroirs, using focus group and tasting. The vision of typicity of terroirs by professionals outside of these terroirs has been studied by a free word association task. RESULTS: This study allowed a clear distinguishing of the typicity of the studied terroirs. Professionals from terroirs identified the global conceptual typicity of their terroirs using various factors, mainly soil, geography and grape variety, whereas professionals outside terroirs expressed their visions of terroirs by reputation or sensory characteristics of wines. Tasting results showed a discrimination of wines based on their typicity and highlighted descriptors involved in sensory perceptual typicity for each studied terroir. CONCLUSIONS: Professionals from terroirs share a common vision of their typicity and identify more typicity factors than professionals outside terroirs. Sensory typicity has been highlighted for five of the six terroirs studied, according to the various descriptors. The study of two populations, from and outside terroirs, shows the gap between the typicities identified by professionals from terroirs and those perceived by professionals outside terroirs. © 2020 Society of Chemical Industry.