RT Journal Article
SR Electronic
T1 Effect of Structural Transformations on Precipitability and Polarity of Red Wine Phenolic Polymers
JF American Journal of Enology and Viticulture
JO Am J Enol Vitic.
FD American Society for Enology and Viticulture
SP ajev.2021.20064
DO 10.5344/ajev.2021.20064
A1 Ingrid Weilack
A1 Christina Schmitz
A1 James F. Harbertson
A1 Fabian Weber
YR 2021
UL http://www.ajevonline.org/content/early/2021/04/06/ajev.2021.20064.abstract
AB Condensed tannins and polymeric pigments are essential red wine components since they contribute to color stability, taste, and mouthfeel. Phenolic polymers in red wine consist of flavan-3-ol monomers as well as anthocyanins and cause the perception of astringency. Due to the chemical heterogeneity of proanthocyanidin polymers, analytical tools for the determination of the polymers’ structural features are limited. The incorporation of anthocyanins increases the structural complexity even more and leaves it almost impossible to assess the influence of structure on the evoked astringency. To obtain a better understanding of the structural diversity of red wine polymers, this study combines forced aging and the FLASH-fractionation of polyphenolic wine extracts to reveal the relationship between phenolic polymers and two physicochemical properties, polarity, and hydrophilicity. Red wine fractions were characterized regarding their polarity, octanol-water partitioning coefficient, protein precipitation assay, UHPLC-MS, and color. Tannin concentrations in wine decreased during forced aging while the concentrations were constant in the corresponding extracts, suggesting an alteration of the precipitation behavior. A simultaneous increase of precipitable polymeric pigments gives rise to the assumption that the incorporation of anthocyanins into tannin molecules alters the interactions with red wine polysaccharides and proteins, which results in lower tannin readings. Finding tannins and polymeric pigments in different FLASH-fractions indicates that precipitability of polymers is affected by the physicochemical properties, which in turn depend on the degree of polymerization as well as degree of pigmentation. The results of this study show that red wine astringency and its sub-qualities may be related to the increase in precipitable polymeric pigments during forced red wine aging and their putative enhanced interaction with wine polysaccharides and can help to better understand astringency mechanisms.