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Reaction Mechanisms of Metals with Hydrogen Sulfide and Thiols in Model Wine. Part 2: Iron- and Copper-Catalyzed Oxidation
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作者:
Gal Y. Kreitman
;
John C. Danilewicz
;
David. W. Jeffery
;
Ryan J. Elias
刊名:Journal of Agricultural and Food Chemistry
出版年:2016
出版时间:May 25, 2016
年:2016
卷:64
期:20
页码:4105-4113
全文大小:448K
年卷期:0
ISSN:1520-5118
文摘
Sulfidic off-odors arising during wine production are frequently removed by Cu(II) fining. In part 1 of this study (
10.1021/acs.jafc.6b00641), the reaction of H
2
S and thiols with Cu(II) was examined; however, the interaction of iron and copper is also known to play an important synergistic role in mediating non-enzymatic wine oxidation. The interaction of these two metals in the oxidation of H
2
S and thiols (cysteine, 3-sulfanylhexan-1-ol, and 6-sulfanylhexan-1-ol) was therefore examined under wine-like conditions. H
2
S and thiols (300 μM) were reacted with Fe(III) (100 or 200 μM) alone and in combination with Cu(II) (25 or 50 μM), and concentrations of H
2
S and thiols, oxygen, and acetaldehyde were monitored over time. H
2
S and thiols were shown to be slowly oxidized in the presence of Fe(III) alone and were not bound to Fe(III) under model wine conditions. However, Cu(II) added to model wine containing Fe(III) was quickly reduced by H
2
S and thiols to form Cu(I) complexes, which then rapidly reduced Fe(III) to Fe(II). Oxidation of Fe(II) in the presence of oxygen regenerated Fe(III) and completed the iron redox cycle. In addition, sulfur-derived oxidation products were observed, and the formation of organic polysulfanes was demonstrated.
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