Identificação, quantificação e potencial antioxidante de antocianinas do resíduo agroindustrial de uva Isabel (Vitis labruscaL.)

The growth of irrigated fruit farming and the increase in new technologies have stimulated the expansion of fruit processing agro-industries, generating a volume of waste that is improperlydiscarded, causing environmental contamination. These residues may have great potential, as in addition to containing sugars, vitamins, mineral salts and fibers, they also have significant levels of bioactive compounds. This research aimed to identify, quantify and purify anthocyanins from grape residue, cultivate Isabel (Vitis LabruscaL.), of frozen pulp processing unit. Anthocyanins were quantified by differential pH and their purification by cartridges Sep-Pak C18. Chromatographic analyses were performed to identify and quantify anthocyanins by CLAE-DAD in reverse phase. The antioxidant activity of purified anthocyanins was evaluated by their ability to scavenge radicals DPPH• (1,1-diphenyl-2-picrylhydrazyl)eABTS•+ (2,2’-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid), taking gallic acid as a reference. Total anthocyanins in grape residue were 35,56 ± 0,33 mg 100g-1. Six major anthocyanins have been identified: cyanidin-3-O-glucoside; delphinidin-3-O-glucoside; malvidin-3-O-glucoside; malvidin-3,5-O-glucoside; pelargonidin-3-O-glucoside; and peonidin-3-O-glucoside, at different concentrations. Malvidin-3-O-glucoside was the most abundant (56.36%) followed by peonidin-3-O-glucoside (17.88%). The purified anthocyanins showed good efficiency against the DPPH• radical (EC50 of 0.14 ± 0.01 g. g DPPH-1 and TEC50 < 5 minutes) and strong sequestration capacity (> 80%). Against the ABTS•+ radical, the anthocyanins showed a sequestration capacity of 241.36 ± 3.74 μmol TEAC. g-1 of sample. It is evident that the residue from the frozen grape pulp industry can be considered a good source of anthocyanins, with potential to be used as a natural antioxidant in new food products.