Stable free radicals as ubiquitous components of red wines |
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Authors: | Monica Rossetto Fabio Vianello Adelio Rigo Urska Vrhovsek Fulvio Mattivi Marina Scarpa |
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Institution: | 1. Dipartimento di Chimica Biologica, Università di Padova, viale G. Colombo 3, Padova, 35121, Italy;2. Dipartimento Laboratorio Analisi e Ricerche, Istituto Agrario di San Michele, San Michele all' Adige, Italy;3. Dipartimento di Fisica and INFM, Università di Trento, via Sommarive 14, Povo, Italy |
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Abstract: | A stable ESR signal, centred at g = 2.0037 ± 0.0002, characterised by a single resonance and assignable to a free radical, was found in all the bottled red wines, both commercial and experimental, that we have examined. The radical concentration was calculated to be in the range of 5–82 nM. After exposure of the wines to air for a few minutes a two fold increase of the ESR signal, followed by a slow decrease with time, was observed. The intensity of ESR signal in experimental red wines, was found to increase with the ageing of the wines and was strictly correlated to the total content of polyphenols. The formation of semiquinone radicals of polyphenols is suggested as one possible mechanism leading to the presence of stable free radicals in red wines. |
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Keywords: | Wine Free radicals Polyphenols ESR |
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