Contenido de polifenoles y actividad antioxidante de extractos de semilla de uva (Vitis vinifera) variedad Malvasia y Tempranillo Polyphenols content and antioxidant activity of grape seed extract (Vitis vinifera) malvasia and tempranillo variety

The study of functional components in grape seed and its potential health benefits represents the greatest contribution in this research, thus taking advantage of an agro-industrial waste. According to important studies grape seed presents secondary metabolites such as polyphenols, antioxidants considered proven health benefits as radical scavengers and inhibitors of lipid peroxidation. The objectives of this research were to optimize the extraction time to obtain hydrophilic extracts and to determine the content of polyphenolic compounds and antioxidant activity of grape seed varieties Malvasia and Tempranillo. The extracts were obtained by Soxhlet method using a methanol:water:acetic acid (90,00:9,50:0,50) and three extraction times: 7, 8 and 9 hours. The total polyphenol content was determined by the Folin Ciocalteu method and antioxidant activity was evaluated by the method of radical cation discoloring of 2.2 ‘-azino-bis-3ethylbenzthiazoline-6-sulphonic acid (ABTS • +), using Trolox as a reference standard. The maximum yield was obtained at 8 hours extraction with values of 5.77 and 6.01% p.p-1 for the Malvasia and Tempranillo variety respectively. The concentration of phenolic compounds was 1.534.85 and 1.048.59 GAE.100g-1 mg sample for the Malvasia and Tempranillo variety respectively. The antioxidant activity for the extract of the Malvasia variety was 54.51 mmol TEAC.100g-1 of sample and 48.46 mmol TEAC.100g-1 sample for the Tempranillo variety. The results suggest that grape seed extracts are a potential source of antioxidants and polyphenolic compounds that can be used in the food and health industry.