Article Figures & Data
Figures
- Figure 1
Schematic representation in which the reduction potential (Eh) of the Fe(III)/Fe(II) couple is measured against a standard hydrogen electrode.
- Scheme 1
(+)-Catechin redox couple.
- Figure 2
Oxidation of ethanol coupled to reduction of hydrogen ions (A) or oxygen (B), which produces the so-called reduction potential in wine.
- Figure 3
Idealized voltammogram representing the forward oxidation of a catechol (H2Q) and reverse reduction of the resulting quinone (Q) in model wine at pH 3.6.
- Scheme 2
Oxidation of ascorbic acid and degradation of dehydroascorbic acid.
- Scheme 3
Quinone/polyphenol and O2/H2O2 redox couples and protonation equilibria.
- Scheme 4
Reaction of (+)-catechin with oxygen.
- Scheme 5
A proposed mechanism for polyphenol oxidation: initiation by the oxidation of Fe(II).
- Scheme 6
Reduction potentials for the (+)-catechin and O2/H2O redox systems at pH 3.6.
- Figure 4
pH dependence of first (EpH1), second (EpH2), and two-electron (EpH(2e)) reduction potentials of the (+)-catechin (Cat) and O2/H2O2 (O2) redox systems. Values for the two-electron reduction potentials are essentially the same and the resulting curves are superimposed.
- Scheme 7
Possible reactions of the hydroperoxyl radical at pH 3.6 by disproportionation and reaction with (+)- catechin, Fe(II), and Fe(III).
- Scheme 8
Oxidation of ethanol by the Fenton reaction.
- Scheme 9
Reduction potentials for the acetaldehyde/ethanol redox couple and first step in the oxidation of ethanol.
- Scheme 10
Radical-chain reaction involved in sulfite autoxidation.
- Scheme 11
Interception of the peroxomonosulfate radical by (+)-catechin.
Tables
- Table 1
Two-electron reduction potentials of quinone/catechol redox couples.
Vol 63 Issue 1
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