Composition and Cellular Localization of Tannins in Grape Seeds during Maturation

Abstract

Cell walls were isolated from seeds of grape berries (Vitis vinifera L.), and proanthocyanidin composition was determined over the course of ripening for different levels of vine water status. During the ripening period the tannins from the cell walls were always more polymerized than those from the inner part of the cell. At maturity this difference becomes more significant compared to véraison, due to a significant increase in the mean degree of polymerization of the cell wall tannins. The tannin composition was typical of grape seed tannins and was quite similar in the two cell fractions studied, but the epicatechin gallate proportion was significantly higher in the cell wall fraction. There were no significant effects of water deficit on composition and polymerization of seed tannins.

Effect of Ethanol on Grape Seed Proanthocyanidin Extraction

“…The percentage of monomeric compounds decreased as the alcohol content increased, whereas the percentage of polymeric proanthocyanidins increased; terminal epicatechin-3-O-gallate doubled its concentration and extension epicatechin-3-O-gallate increased its percentage, although to a lesser extent. Geny et al (2003) found a higher proportion of epicatechin-3-O-gallate in the proanthocyanidins located in the seed cell wall fraction than in the inner part of the cell, so that a greater degradation of the cell walls with increasing alcohol content could promote a higher release of more galloylated proanthocyanidins. Similarly, Koyama et al (2007) indicated that the galloylated proanthocyanidins, which present higher hydrophobicity, might be selectively trapped by internal components of the seed cells and be released with the aid of increased ethanol concentrations.…”

Influence of Maceration Temperature in Red Wine Vinification on Extraction of Phenolics from Berry Skins and Seeds of Grape (Vitis vinifera)

“…Alternatively, the different cellular localization of proanthocyanidins with different compositions might explain this selectivity. 8,32,33) The decrease in the concentrations of skin phenolics after reaching a maximum ( Fig. 2A, B, C) might be due to the adsorption of extracted polyphenols by yeast lees and/or grape solids, degradation, oxidation, or condensation.…”

Characterization of a Grapevine R2R3-MYB Transcription Factor That Regulates the Phenylpropanoid Pathway

“…Extraction of CTs was carried out as described by Geny et al (2003) and measurements were performed according to the method of Saucier et al (2001). HPLC analyses were carried out on a Spectra Physics system fitted with a UV visible detector driven by a PC1000 system.…”