Studying the redox state of wines under oxidative processes with a multi-parametric analysis

Abstract

The detection of reducing compounds such as phenolic acids, anthocyanins or tannins is of prime importance to decipher on the antioxidant and anti-aging properties of wines. Spectrophotometric methods (ABTS, DPPH) are the reference methods, but their major limitation is their interference with other reducing compounds present in wines.¹ In this context, electrochemical methods are of great interest, as they are fast, easy to use and well selective for such species. Various procedures are described in the literature, based on voltammetric techniques associated with carbon electrodes, in some cases functionalized to improve detection sensitivity and/or increase selectivity towards interfering compounds.^2-4 Approaches based on the use of screen-printed disposable sensors (PolyScan Vinventions) made also possible to obtain a fingerprint and/or classification of certain phenolic compounds, or to study different alternatives to oak wood for the wine industry.^5,6 The research performed by the RedoxWine joint laboratory (CBMN – Biolaffort) is first devoted to the development of analytical protocols based on electrochemical methods to detect some key molecules in wine and define a signature of its redox state in real time. Several electrochemical sensors are developed to study the relationships between reductants, i.e. concentrations of sulfite, phenols and derivatives, and the levels of oxidants, first oxygen and daughter Reactive Oxygen Species (H₂O₂, O₂°-), generated or provided in a controlled manner. We are thus studying wine responses under controlled oxidative stress, starting from normoxic conditions to chemically forced conditions (additions of known concentrations of O₂, H₂O₂ or by direct electrochemical oxidation of the wines) to accelerate matrix ageing processes. The evolution of the wines redox chemistry is eventually studied using a combination of spectroscopic and electrochemical techniques: redox signature, sulfite, dissolved O₂, pH, color (CieLab) and thiols.⁷

References

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[2] Makhotkina, O., Kilmartin, P.A., Analytica Chimica Acta, 2010, 668, 155-165

[3] Barroso, M. F., et al. Biosensors Bioelectronics, 2011, 30, 1-12

[4] Gonzalez, A. et al. Food Chem. 2018, 269, 1-8

[5] Kilmartin, P.A., Electrochem. Comm. 2016, 67, 39-42

[6] Wirth, J. et al. Beverages, 2021, 7, 1

[7] Dauphin, A., Guilbault, S., Arbault, S., 2025, submitted