Brazilian red wines made from the hybrid grape cultivar Isabel: phenolic composition and antioxidant capacity

Abstract

The hybrid grape cultivar Isabel (V. vinifera x V. labrusca) accounts for about 50% of Brazilian grape production. The anthocyanin composition of the Isabel grape is known, but there is no data for the red wines produced with it. By means of HPLC-DAD-ESI-MS(n) we have studied the most important low molecular phenolic compounds in Isabel red table wines (anthocyanins, pyranoanthocyanins, flavonols and hydroxycinnamic acid derivatives) in order to look for differences between these and V. vinifera red wines, and also their antioxidant capacity using the DPPH method. The anthocyanins found in Isabel red wines are mainly based on malvidin and they were the expected 3-glucosides and the non-vinifera characteristic 3,5-diglucosides including several minor compounds, such as the newly reported cis isomer of malvidin 3-(6''-coumaroyl)-glucoside-5-glucoside. As also found in V. vinifera red wines, Isabel red wines contain pyranoanthocyanins formed from anthocyanidin 3-glucosides during alcoholic fermentation and wine aging (vitisins A and B, and hydroxyphenyl-pyranoanthocyanins). The content of malvidin- and peonidin-based hydroxyphenyl-pyranoanthocyanins derived from p-coumaric and caffeic acids accounted importantly for the pool of low molecular red wine pigments in Isabel wines. The occurrence of other non-anthocyanin phenolic compounds, like hydroxycinnamic acid derivatives and flavonols, are newly reported for Isabel red wines. In contrast to the differences found in the anthocyanins profiles, the flavonols and hydroxycinnamic acid derivatives present in Isabel wines were the same as those in V. vinifera red wines. The content of flavonols is relatively low, but the content in hydroxycinnamic acid derivatives is high in Isabel red wines. Finally, Isabel red wines showed low-medium antioxidant capacity when compared to V. vinifera red wines.