Uncovering the influence of antioxidants on polyphenol oxidation in wines using an electrochemical method: Cyclic voltammetry

Electrochemistry of White Wine Polyphenols Using PEDOT Modified Electrodes

“…Such behavior is typical of an absorbed layer of redox active species, while some smaller diffusional component may serve to bring the value down from 1.0. At the same time, the oxidation of caffeic acid was largely completed by 600 mV, at which point the current returned to the background response due to the PEDOT conducting polymer itself (Figure 2a), and without the ongoing current expected for a process under diffusion-control typical of caffeic acid at a glassy carbon electrode [14]. Instead, the oxidation and subsequent reduction peaks point to the electrochemistry of an absorbed species.…”

“…Poly-3,4-ethylenedioxythiophene (PEDOT) has been of particular interest [11][12][13], with improved sensitivity and antifouling properties. Separate current signals due to ascorbic acid and wine polyphenols have been obtained, which can merge at glassy carbon electrodes due to inhibitory effects of adsorbed polyphenols on ascorbic acid oxidation [14,15]. In further work with PEDOT electrodes, an improved response for tea catechins was obtained compared to glassy carbon electrodes [16], and the most responsive PEDOT films were those prepared originally in a propylene carbonate electrolyte [17].…”

Voltammetric and spectrometric determination of antioxidant capacity of selected wines

“…The total polyphenol index of wines was also determined by using an electronic tongue and multivariate calibration, but the relationship between polyphenol content and antioxidant capacity was not discussed in this approach [16]. Furthermore, most papers have A c c e p t e d M a n u s c r i p t 5 focused on a low number of samples, mostly red and white wines, from a single geographical area [6,11,14,16,17]. Thus, the aim of this work was to evaluate the antioxidant activity of a range of wines from geographically distinct locations, different quality levels and varied production techniques.…”

“…It is interesting to highlight that wine´s phenolic profile is different from grapes, a fact that can be attributed to the extraction process, which increases the content, and also to the fermentation process, that modifies substances [6,7,8]. Thus, owing to the health properties of wines, in which the phenolic antioxidants play a crucial role, it is indispensable to have methods capable of measuring wine´s antioxidant activity [9,10].…”

“…Hence, natural phenolic and non-phenolic compounds and also some wine additives present native electroactivity, which could lead to the observed voltammetric profile. For instance, it was observed that sulfur dioxide may cause some distortions on cyclic voltammograms obtained for wine or phenolic compounds in model wine solutions [6,23,24]. However, such distortions might be corrected and minimized in differential pulse voltammetry.…”