EPR STUDY OF ANTIOXIDANT CHARACTERISTICS OF SOME WINE

V.Miclaus2, G.Damian1 , Dina Petrisor1, Gabriella Schmutzer1,  Melita Butuza2,
Claudia Cimpoiu2

1  Faculty of Physics, “Babeş-Bolyai” University, 1A Kogalniceanu,
400084-Cluj-Napoca, Romania
2 Chemistry  and Chemical Engineering Faculty, “Babes-Bolyai” University , Arany Janos no. 11, 400028 Cluj Napoca, Romania

Fig.1 The variation of the Tempol EPR signal in white wine

Electron Paramagnetic Resonance (EPR) spectroscopy, was used to study the antioxidant characteristics in red and white wines. The antioxidant proprieties of wines appear to be associated with the polyphenolics [1]. Red and white wines contain a variety of polyphenolic compounds. Polyphenols concentrations varied largely among the different wines. Most red wines had higher amounts of polyphenols than white wines. Aging is the main factor influencing the antioxidant activity of red wine [2]. Type of grapes, moment, conditions and processing technology, even maintain conditions are important factors that influence the antioxidant activity of wines. The antioxidant activity of polyphenolics is studied, in general, through three different methods: chemical, biochemical and biologic method [3]. The method used in this research concern the utilization of stable free radicals from nitrone classes (nitroxide radicals), named “spin label”. Nitroxide radicals were proposed for the quantitative study of the redox properties of biological systems. The nitoxide radicals are relatively stable towards oxidation but they can be easily reduced to the corresponding hydroxylamines:
We used a commonly encountered nitrone spin trap, nitroxidic radical Tempol (2,2,6,6-tetramethyl-4-hydroxypiperidine-oxyl). The intensity of EPR signal in experimental red and white wines, was found to decrease in time and was correlated to the total content of polyphenols [Fig.1].

References
[1] Lopez-Velez M, Martinez-Martinez F, Del Valle-Ribes C, The study of phenolic compounds as natural antioxidants in wine, Crit Rev Food Sci Nutr. 2003;43(3):233-44
[2] Pellegrini N, Simonetti P, Gardana C, Brenna O, Brighenti F, Pietta P, Polyphenol content and total antioxidant activity of vini novelli (young red wines), J Agric Food Chem. 2000 Mar;48(3):732-5
[3] Brenna, O. V.; Pagliarini, E. Multivariate analysis of antioxidant power and polyhphenolic composition in red wines. J. Agric. Food Chem. 2001, 49, 4841-4844.