Revista Brasileira de Fruticultura
Print version ISSN 0100-2945
SOARES, Marcia et al. Phenolic compounds and antioxidant activity in skin of Niagara and Isabel grapes. Rev. Bras. Frutic. [online]. 2008, vol.30, n.1, pp. 59-64. ISSN 0100-2945. http://dx.doi.org/10.1590/S0100-29452008000100013.
Grape production in Brazil is located in the South, Southeast and Northeast regions. It is a consolidated activity of great social and economical importance mainly in Rio Grande do Sul and Santa Catarina states. These states are responsible for 97% of national wine production. Isabel grape is one of the main varieties of Vitis labrusca and Niagara Rosada is resulted from a somatic mutation in Niagara Branca grape (Vitis labrusca L. x Vitis vinifera L.). These varieties are well established as table grapes being rustier than others. This work intends to determine the total phenolic compounds content, by using acetone as solvent in different concentrations as well as the antioxidant activity, anthocyanins content, flavonoids in skin of Niagara Rosada and Isabel grapes. The results for total phenolic content in 75% acetone extract ranged, in average, from 1026.69 to 1242.78 mg GAE/100g of dry weight in Isabel and Niagara varieties, respectively. Antioxidant activity presented values of 89.22 and 157.31 µmol TEAC/g of sample with ABTS method and of 197.00 and 189.82 µmol TEAC/g of sample with DPPH method for Isabel and Niagara varieties, respectively. Anthocyanins content was low when compared to other fruits. TEAC values depended on polyphenols values and it was observed a positive correlation among averages of total polyphenol content and TEAC values, indicating a strong influence. This can be probably due to the phytochemical compounds present in grape skins.
Keywords : Vitis labrusca; Vitis vinifera L; antioxidant capacity; poliphenol; anthocyanins; flavonoids.