Otimização da extração aquosa de polifenois do bagaço de mirtilo e do resíduo da vinificação

Abstract

Fruit processing and wine industries generate large quantities of solid wastes. Blueberry bagasse and grape pomace are some of them which are discarded or underutilized. However, it still is a rich source of bioactive compounds with putative beneficial effects to human health. The aim of this work was to optimize methodologies of aqueous extraction of anthocyanins present in blueberry bagasse and winemaking residue of Malbec grapes. Final solutions were characterized in relation to antioxidant activity and anthocyanin profile identification. Conventional extraction methodologies and use of microwave irradiation to obtain solutions rich in anthocyanins were tested. Blueberry bagasse was produced with the purpose of simulating industrial processing, from a mixture of commercially available cultivars (Duke, Bluecrop and Climax). Winemaking residues of Malbec grapes were donated by Vinícola Velho Amâncio (Itaara, RS) from 2016 harvesting year. The aqueous blueberry extract was obtained under optimum extraction conditions defined by the model determined using a central composite design (CCD) and the response surface methodology to evaluate the behavior of total monomeric anthocyanins using the pH-differential method. Independent variables for blueberry pomace extraction optimization were temperature (38 - 100 ° C) and extraction time (5 - 60 minutes). Optimal condition (100 ° C for 5 minutes) was able to recover more than 75% of the anthocyanins present in blueberry bagasse. Major anthocyanin was malvidin-3-galactoside (19%). Aqueous extracts of winemaking residue were obtained by microwave assisted extraction. The final behavior was majorly determined by the time under extraction and the highest recovery was predicted as using 15 minutes under 700 W. It was also determined by CCD and the response surface methodology. Extraction time (2 - 15 min) and power (350 - 700 W) were the independent variables studied for maximal response of total monomeric anthocyanins. Model’s best condition was able to recover more than 70% of anthocyanins present in grape residue. Final solution was majorly composed of malvidin-3-p-coumaroyl glycoside (42%). Aqueous extracts of blueberry bagasse and winemaking residue presented good antioxidant capacity and potential application as nutraceuticals in food or pharmaceutical industry. Present study optimized "green" methodologies for the recovery of bioactives present in fruit residues. Proposed methods are simple and fast and can be transposed to industrial scale.