Journal article

Influence of light exposure, ethanol and copper(II) on the formation of a precursor for xanthylium cations from tartaric acid

AC Clark, GR Scollary

Australian Journal of Grape and Wine Research | Published : 2003

Abstract

The production of xanthylium cation pigments was greatly increased when an aged, tartaric acid buffered, 12% (v/v) aqueous ethanol solution was used in a model white wine system. This suggested the formation of a precursor to the pigments during the ageing of the tartaric acid solution. On examining factors responsible for the generation of tartaric acid oxidation products in wine-like solutions it was observed that on exposure of samples to sunlight, glyoxylic acid, a known precursor to xanthylium cations, was produced. The production of glyoxylic acid was achieved in both the absence and presence of ethanol and copper(II). Hydrogen peroxide was also detected in these solutions. The results..

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University of Melbourne Researchers