Macrowine 2021
IVES 9 IVES Conference Series 9 Understanding sweetness of dry wines: first evidence of astilbin isomers in red wines and quantitation in a one-century range of vintages

Understanding sweetness of dry wines: first evidence of astilbin isomers in red wines and quantitation in a one-century range of vintages

Abstract

The gustatory balance of wines relies on sweetness, bitterness and sourness. In dry wines, sweetness does not result from the presence of residual sugar as in sweet wines, but is due to other non-volatile compounds. Such taste-active compounds are released during winemaking, by grapes, yeasts or oak wood and belong numerous chemical families [1]. Beyond this diversity, stereochemistry of molecules can also influence their sensory properties [2]. However, the molecular determinants associated with this taste have only been partially elucidated. Astilbin (2R, 3R) was recently reported to contribute to wine sweetness [3]. As its aglycon contains two stereogenic centers, three other stereoisomers may be present: neoisoastilbin (2S, 3R), isoastilbin (2R, 3S), and neoastilbin (2S, 3S). These compounds have already been observed in natural products, but never in wine. This work aimed at assaying their presence for the first time in wines as well as their taste properties.The isomers were synthesized from astilbin and purified by semi-preparative HPLC. Their content was assayed by developing a UHPLC-Q-Exactive quantification method. The method was applied to screen astilbin and isomers in various wines, especially in different vintages from the same estate. Sensory analysis highlighted the sweet taste of these stereoisomers whose intensity varied according to their configuration. Quantification results revealed that while young wines contained higher concentrations of astilbin than the old ones, the concentrations of the other isomers, mainly neoastilbin, were higher in the old wines, suggesting their formation over time.These results highlight the contribution of astilbin isomers in wine sweetness. More generally, this study brings new insights to understand the chemical origin of wine taste.

DOI:

Publication date: September 17, 2021

Issue: Macrowine 2021

Type: Article

Authors

Marie Le Scanff , Syntia FAYAD, Axel MARCHAL, 

Unité de recherche Œnologie, EA 4577, USC 1366 INRA, ISVV, Université de Bordeaux, F33882 Villenave d’Ornon, France 

Contact the author

Keywords

sweetness, sensory analysis, taste, isomers, wines

Citation

Related articles…

Development of a new indicator of grape skin ripening in relation to Botrytis cinerea susceptibility

The bunch rot induced by Botrytis cinerea is an important disease of grapevine that causes a diminution of grape quality and a considerable yield loss leading to an economic loss

Bentonite fining in cold wines: prediction tests, reduced efficiency and possibilities to avoid additional fining treatments

Bentonite fining is widely used to prevent protein haze in white wines. Most wineries use laboratory-scale fining trials to define the appropriate amount of bentonite to be used in the cellar. Those pre-tests need to mimic as much as possible the industrial scale fining procedure to determine the exact amount of bentonite necessary for protein stability. Nevertheless it is frequent that, after fining with the recommended amount of bentonite, wines appear still unstable and need an additional fining treatment. It remains a major challenge to understand why the same wine, fined with the same dosage of the same bentonite, achieves stability in the lab, but not in the cellar.

Estudios de zonificación vitícola en España

La delimitación y caracterización de zonas vitícolas plantea en España problemas específicos no sólo por las características peculiares del territorio sino también por el tamaño

Phylloxera root infection drives vineyard water

Most of the rootstocks used in viticulture today are partly resistant against grape phylloxera (Daktulosphaira vitifoliae Fitch) and host phylloxera on the root system without conspicuous negative impacts on fruit production).

Impact of climate variability and change on grape yield in Italy

Viticulture is entangled with weather and climate. Therefore, areas currently suitable for grape production can be challenged by climate change. Winegrowers in Italy already experiences the effect of climate change, especially in the form of warmer growing season, more frequent drought periods, and increased frequency of weather extremes.
The aim of this study is to investigate the impact of climate variability and change on grape yield in Italy to provide winegrowers the information needed to make their business more sustainable and resilient to climate change. We computed a specific range of bioclimatic indices, selected by the International Organisation of Vine and Wine (OIV), and correlated them to grape yield data. We have worked in collaboration with some wine consortiums in northern and central Italy, which provided grape yield data for our analysis.
Using climate variables from the E-OBS dataset we investigate how the bioclimatic indices changed in the past, and the impact of this change on grape productivity in the study areas. The climate impact on productivity is also investigated by using high-resolution convection-permitting models (CPMs – 2.2 horizontal resolution), with the purpose of estimating productivity in future emission scenarios. The CPMs are likely the best available option for this kind of impact studies since they allow a better representation of small-scale processes and features, explicitly resolve deep convection, and show an improved representation of extremes. In our study, we also compare CPMs with regional climate models (RCMs – 12 km horizontal resolution) to assess the added value of high-resolution models for impact studies. Further development of our study will lead to assessing the future suitability for vine cultivation and could lead to the construction of a statistical model for future projection of grape yield.