Avaliação da capacidade antioxidante em frutas produzidas na região sul do rs

A capacidade antioxidante e sua correlacao com fenois e antocianinas foi estudada em cultivares de amora-preta, morango e mirtilo. As frutas foram colhidos no estadio de maturacao maduro provenientes do Programa de Melhoramento Genetico da Embrapa Clima Temperado, Pelotas-RS, e foram imediatamente congeladas por submersao em nitrogenio liquido e armazenadas a -18 o C ate o momento do preparo das amostras. O desenho experimental foi completamente casualizado, com tres repeticoes de cinco frutos. Os resultados foram analisados por ANOVA e as diferencas significativas foram analisadas usando teste de Tukey. A capacidade antioxidante dos extratos das frutas (TEAC) foi medida pelo monitoramento da mudanca na absorbância do radical livre a 515nm pelo metodo DPPH e 734nm pelo metodo ABTS, e, expressa em m moles de equivalentes de Trolox. Os valores de TEAC-DPPH, variaram de 7,06 e 13,22 µmols de TE/g de fruta, para as cvs. de amora-preta; de 5,17 a 7,72µmols de TE/g de fruta para as cvs. de morango;  e de 4,3 a 7,26 µmols de TE/g de fruta para as cvs. de mirtilo. Para morango e amora-preta, encontrou-se correlacao direta entre fenois totais e capacidade antioxidante, enquanto que para antocianinas totais somente correlacionaram-se com capacidade antioxidante para todas cultivares de amora-preta. Entre as frutas avaliadas, a cv. Xavante de amora-preta foi superior para capacidade antioxidante, sendo que os metodos TEAC-ABTS e TEAC-DPPH mostraram-se equivalentes. Palavras-chave: fenois totais, antocianinas, trolox e correlacao. ABSTRACT The antioxidant capacity and its correlation with phenols and total anthocyanins among blackberry cultivars, strawberry and bluberry was studied. Mature and sound appearance fruits were picked from an experimental orchard of the Program of Genetic Improvement of Embrapa Temperate Climate, Pelotas-RS. Fruits were immediately frozen for submersion in liquid nitrogen and stored in freezer at -18oC until the sample preparation. The experimental design used was a completely randomized design, with fifteen fruits that were divided into three replications of five fruit each. The results were analyzed by ANOVA, and significant differences were determined using Tukey’s test. The antioxidant capacity (TEAC) was measured by the DPPH method at 515nm ABTS method at 734nm, and expressed in micromolar of trolox equivalent (µM TE). The values of TEAC-DPPH ranged from 7.06 to 13.22µM TE/FW to blackberries, from 5.17 to 7.72 to strawberries, and from 4.3 to 7.26 to blueberries cultivars. The good correlation for TEAC in strawberries samples of DPPH and ABTS assays allow to infer that both of them are equivalent to evaluate antioxidant capacity of fruits. The total phenolics contents were strongly correlated with the antioxidant capacity in strawberries and blackberries. The anthocyanins contents were correlated with antioxidant capacity only in blackberries. Among the tested fruits, blackberry had the highest antioxidant capacity for both methods. Key Words: total phenolics, anthocyanins, trolox and correlation.