In the wine industry there is a generalized need for rapid evaluation of grape and wine resistance to oxidation, in order to develop tailored oxygen management strategies. We have conducted a series of studies to evaluate linear sweep voltammetry for rapid assessment of grape and wine oxidation, using antioxidant sensing carbon paste disposable electrodes. Voltammograms were obtained in the 0-1200 mV range. Analysis required approx. 30 sec, no sample preparation, and can be carried out in the winery. Disposable electrodes allowed bypassing time-consuming cleaning procedures that are often associated with wine voltammetry.The oxidation patterns of several musts from white grapes were studied under conditions of controlled oxidation (eg. consumption of sequential oxygen saturations). Musts exhibiting higher current in the 0-600 mV region of the voltammograms were characterized by higher oxygen consumption rates, indicating greater ability to combine oxygen. Absorbance values at 320 nm suggested that this was due to higher content of hydroxycinnamic acids. An estimate of the latter could be therefore obtained voltammetrically. Changes to voltammetric profiles following oxygen consumption were must-dependant. With each oxygen saturation, musts with higher 0-600 mV current as well as total current (0-1200 mV) showed a decrease in selected voltammetric parameters. Other patterns were also observed, including cases where, in spite of oxygen being consumed, no change in must voltammetric occurred. For the musts tested, decrease of total current over 3 sequential saturations was found to be linked to the caftaric/GRP ratio.Oxidation signatures of different white wines were also obtained, showing characteristic features similar to those obtained during oxidation of caffeic acid, catechin, and ascorbic acid in a reference wine.The voltammetric setup developed allowed rapid monitoring of the evolution of grape and wine phenolics during oxygen consumption, both in the laboratory and in the winery.

Oxidation signature of grape and wine by linear sweep voltammetry using disposable carbon electrodes: Toward a rapid assessment of oxidation resistance

248th National Meeting (2014)

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