About the impact of oak ellagitannins on wine odoriferous thiols under acidic and oxidation conditions. Issue 20 (20th May 2015)

• Record Type: Journal Article
• Authors: Petit, Emilie; Jacquet, Rémi; Pouységu, Laurent; Deffieux, Denis; Quideau, Stéphane
• Is Part Of: Tetrahedron. Volume 71:Issue 20(2015)
• Page Start: 2991
• Page End: 2998
• Publication Date: 2015-05-20
• Subjects: Condensation -- Ellagitannins -- Odoriferous thiols -- Oxidation -- Polyphenols -- Wine; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tet.2015.02.036
• Languages: English
• ISSNs: 0040-4020

Abstract

Abstract: The decrease of the level of characteristic odoriferous thiols in wines has been in part imputed to chemical transformations that take place during aging of wines in oak-made barrels and subsequent storage in bottles. Oxygen dissolved in wines certainly plays a role in such chemical transformations, such as the oxidation of catecholic catechins into thiol-trapping ortho -quinones. However, wines aged in barrels or supplemented with oak chips contain pyrogallolic C -glucosidic ellagitannins, which can also trap thiols in mildly acidic and oxygenated wine solutions by both nucleophilic substitution and oxidative addition reactions. The C -glucosidic ellagitannin vescalagin and methyl gallate were chosen as substrates to investigate these reactions in the presence of two well-known wine odoriferous thiols, 3-sulfanylhexan-1-ol (3SH) and 2-furanmethanethiol (2FMT). Three novel thio-vescalagin condensates were thus hemisynthesized under acidic conditions, and the FeCl3 -mediated oxidation of methyl gallate furnish different thiogallate adducts under conditions applicable to the oxidative hemisynthesis of thio-ellagitannin adducts. Graphical abstract: