Potencial de sucos integrais de uvas produzidas no Vale do São Francisco, Brasil: caracterização físico-química, atividade antioxidante e avaliação sensorial

Abstract

The São Francisco Valley (SFV), the largest second winegrowing region of the Brazil, has been investing in the selection of grapes to elaborate whole juices. The aim of this work was to evaluate the physic-chemical composition, antioxidant activity, profile and acceptance sensory of six grape juices produced from grapes Vitis labrusca (Isabel Precoce), Vitis vinifera (Alicante Bouschet, Tempranillo, Syrah) and hybrids (BRS BRS Cora and Violet) cultivated in the SFV. All physic-chemical parameters were analyzed by standardizes methods. As the Folin-Ciocalteu method is not validated for grape juice, this method was validated. Linearity was demonstrated between 1.20 to 6.00 g L-1 of phenolics in juice and no significant matrix effects were observed in this range. Mean recoveries ranged from 85% to 87%. The theoretical limits of detection and quantification were 0.65 and 0.71 g L-1, respectively. Precision under repeatability and intermediate precision conditions was confirmed. The physico-chemical parameters varied according to grape cultivar and the following composition was observed: density (1.064 to 1.090), suspended solids (0.36 to 4.82%), soluble solids (15.59 to 21.64 °Brix), pH (3.47 to 3.89), total acidity (0.64 to 1.47 g 100 mL-1), TSS/TA ratio (10.67 to 34.03), volatile acidity (0.017 to 0.024 g 100 mL-1), ethanol (0.0 to 0.35 % v v-1), total sugars (16.75 to 21.85 g 100 mL-1), glucose and fructose (5.17 to 10.69 g 100 mL-1) and sucrose (0.0 to 0.11 g 100 mL-1). Tartaric and malic acids were predominant (348.78 and 443.43 g 100 mL-1, respectively). The BRS Cora juice exhibited the highest total phenolics content (4.21 g L-1) and the juice BRS Violeta presented the highest contend of anthocyanins (1530.54 mg L-1). Juices showed high in vitro antioxidant activity. The sensory profile of grape juices were generated by a panel of nine trained judges, employing Quantitative Descriptive Analysis. The overall acceptance of the samples was evaluated by 120 consumers. The Isabel Precoce and BRS Cora juices presented similar sensory profile, due to their highest intensity of fox and red fruit aroma and flavor. These juices were the most accepted samples and greatest purchase intention. The Vitis vinifera grape juices were similarly characterized by molasses (“rapadura”) and dry/tea aromas and flavors. BRS Violeta juice showed the most distinct sensory profile, described by attributes lower acceptance. BRS Cora juice was highlighted among the evaluated samples, showed the highest phenolic compounds content, high antioxidant activity and good acceptance by consumers.