The "Submédio do Vale do São Francisco" (S.V.S.F.), located in the Brazilian Northeast, is an emerging winemaking region in South America. Touriga Nacional (T.N.) grapes originated in Portugal, thrive under the climatic conditions found in the S.V.S.F. The effects of extended maceration on different parameters of red wine must produced with T.N. grapes from two harvest years from S.V.S.F. were studied. Increased maceration time (16 to 20 days) resulted in greater total phenolic contents (40 to 85%) compared to eight days of maceration, along with higher antiradical activity (15 to 36%). Regardless of the harvest year, the antiradical activity was mostly related to the contents of resveratrol, (+)-catechin, isorhamnetin-3-O-glucosidase, and (−)-epigallocatechin gallate. In contrast, color intensity was not affected. The increase in the maceration period induced a positive effect on the phenolic composition, which was reflected in the higher antiradical activity of T.N. red wine.

The use of oak chips is an alternative method to the traditional barrels in winemaking in order to improve the aged quality of the red wines. This study investigated the influence of adding of oak chips during the fermentation process on phenolic compounds profile and antioxidant activity. The American (Quercus alba) and/or French (Quercus petreae) oak chips were added (4 g L⁻¹ doses) in the alcoholic fermentation and malolactic fermentation or malolactic fermentation alone. Results indicated that Syrah tropical wines presented higher levels (≥265 mg L⁻¹) of phenolic compounds compared to wines fermented with oak chips (223–254 mg L⁻¹). Twenty-five phenolics were identified among the wine samples, with gallic (70.67 mg L⁻¹) and malvidin-3-O-glucoside (68.30 mg L⁻¹) as the main compounds. However, the wine with French oak chip added during malolactic fermentation showed a higher antioxidant activity, when using ORAC assay. This study offers a practical application of oak chips in winemaking process as an alternative to produce high quality young red wines with low cost to the wineries in places of oak barrels.

The present study evaluated the influence of training systems and rootstocks on the quality of Syrah tropical wines, produced at São Francisco Valley, Brazil. For this purpose, physicochemical characteristics, phenolic composition, and antioxidant activity were assessed in wines produced with grapes grown under divided trellis system (lyre) and esparlier or vertical shoot position (VSP) training systems, grafted on IAC 572, IAC 766 and Paulsen 1103 rootsotcks and harvested at two different periods. Harvest season had the strongest influence on wine quality, followed by the rootstock. Regardless of the training system and climatic variability between the harvests, the use of the IAC 766 rootstock led to wines with higher alcohol, anthocyanins contents and color intensity. The interaction between the espalier training system and the rootstock IAC 766 resulted in higher flavonol content, phenolic acids, and malvidin-3-O-glucoside, which was detected as the major phenolic as quantified by HPLC. This wine also presented significant levels of procyanidins A2 and B2, which showed a positive correlation with the antioxidant activity.