In vitro digestion of grape residue obtained from juice centrifugation: bioactive potential and stability of anthocyanins

Abstract

Currently the search for alternative sources of natural pigments has stimulated the development of research in different sectors of viticulture. The residue of this study was obtained from the centrifugation step of grape juice clarification. This residue is rich in anthocyanins, natural pigments that, besides the ability to confer color, also have high antioxidant capacity, antiproliferative activity and cardioprotective properties. The objective of the present work was to evaluate the bioactive potential and bioaccessibility of mono- and diglycosides anthocyanins assessed by in vitro digestion of the grape juice residue from Isabel (V. labrusca L.). The in vitro gastrointestinal simulation was performed as described by Minekus et al., (2014), by simulating the physiological conditions of the oral, gastric and intestinal phases. After the oral, gastric and intestinal digestion, the digested fractions were analyzed for antioxidant activity by the ABTS and DPPH methods and individual anthocyanins were determined by HPLC-DAD. The phenolics malvidin3-5-diglycoside, malvidin3-O-glycoside and peonidin3-O-glycoside were identified at the end of the digestion process, with their concentrations significantly reduced (p<0.05) in the intestinal phase. The malvidin3-O-glycoside was 6.93% bioaccessible. The use of this residue as a new source of natural pigments contributes to the development of the wine sector and to sustainable viticulture.