Total antioxidant status of Argentine red wines

REPETTO, MARISA; BOVERIS, ALBERTO

Rio Grande do Sul, Brasil

Simposio; Simposio Internacional Vinho e Saúde-vinho como alimento natural.; 2005

Cesar Filho, J. and Monfroi V.

Wine is a complex biological fluid containing water, ethanol, sugars and notably phenolics. The term phenolics are used to describe the large family of plant derived secondary metabolites which contain at least one benzene ring with a phenolic hydroxyl group attached. In general, the phenolics can be separated into two main groups, the flavonoids and non-flavonoids. Flavonoids are found in high concentrations in the leaf and fruit epidermis. The most common flavonoids in red wine are the flavolos, flavan-3-ols, and the anthocyanins. The main non-flavonoids are derivatives of benzoic and cinnamic acids, and their respective aldehydes. Wood aged wines have their own range of hydrolysable tannins and products of lignin degradation including gallic and ellagic acids. In addition the stilbenes are an important family of non-flavonoids. Polyphenols are common dietary components of vegetables, fruits, red wine and tea, among other sources. Regarding its abundance in these compounds, red wine is probably the richest polyphenol containing beverage. On an average, one litter of red wine contains 2 grams of total polyphenols, from which anthocyanins constitutes about 65-70%. Neutral polyphenols including flavonols as catechin and epicatechin, procyanidins and flavonols as quercetin and mirycetin constitutes around 15 %. The remaining fraction is composed of hydroxybenzoic and hydroxyl cinnamic acids such as gallic and caffeic acid. In red wine the phenolics are responsible for amongst other things, colour, taste, aroma and antimicrobial characteristics. Phenolics can be derived from grape tissue, vine leaves and stems, yeasts or wood ageing. Flavonoids which share a basic structure with vitamin E are potent scavengers of free radicals such as hydroxyl and superoxide radicals and also chelators of transient elements. The aim of this work was to applicant a colorimetric method for the quantitative in vitro determination of total antioxidant status of Argentinean red wines. Oxidation of 2,2`-azino-di-[3-ethylbenzthiazoline sulphonate] (ABTS), incubated with a peroxidase (metmyoglobin) and H2O2leads to the formation of the stable blue-green coloured radical cation (ABTS+). The ABTS derived radicals readily react with free radical scavengers. The reaction can be carried out in water and can be readily followed by the decrease in absorbance at 600 nm, after exactly 3 minutes after the substrate addition. Antioxidants in the added wine sample cause suppression of this colour production to a degree which is proportional to their concentration due to their capacity to reduce the pre-formed radical. The capacity of a compound or complex sample to bleach the absorbance has been employed as an index of their antioxidant capacity. Six different commercial Argentinean red wines were tested, Cabernet Sauvignon, Syrah, Malbec, Tempranillo. Wines were chosen from a range of origins, grape varieties and manufactured methods. Samples were eluted 1/10 in deionised water. Results were compared to a standard solution (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid).The six wine samples exhibited a similar range of antioxidant capacity. The total antioxidant status were: Cabernet Sauvignon 17 ± 2 mM , Syrah 16 ± 1 mM, Malbec 18 ± 2 mM 2 mM, Tempranillo 18 ± 3 mM, all wines of the same origin. Other Cavernet Sauvignon variety wines showed different antioxidant content: 14 ± 2 mM" w:st="on" />2 mM and 21 ± 1 mM, for wines of bad and high qualities respectively. The results demonstrate that the different phenolic profiles of wines can produce varying antioxidant content, similar as was reported by other methods.This method provides a simple, reproducible and sensible measure of the amount of antioxidants present in red wine and allows evaluate the possibility of relating the reaction profiles to the antioxidant capacity of the phenolic content of red wine. This approach is particularly useful for testing the antioxidant capacity of complex mixtures. The chain breaking antioxidants are molecules with the capacity to transform active radicals into inactive species. The different phenolic profiles of wines can produce varying antioxidant and biological activities which opens up the possibility that some red wines have the specific potential to provide enhanced health benefits to the consumer.