Digestibility, bioactivity and prebiotic potential of phenolics released from whole gold kiwifruit and pomace by in vitro gastrointestinal digestion and colonic fermentation

Abstract

The aim of this study was to evaluate the release of phenolics, biological activity variation and prebiotic potential of whole gold kiwifruit and pomace by in vitro digestion and colonic fermentation. The released phenolics of whole kiwifruit and pomace after digestion were 99.53 and 101.04 mg GAE per 100 g FW, respectively. Six compounds were quantified, and catechin, gallic and caffeic acid were mainly released in the oral phase, protocatechuic acid in the gastric phase, and coumaric and hydroxybenzoic acid during fermentation. The whole kiwifruit possessed higher antioxidant activity than the pomace, while both showed decreases during the whole digestion and fermentation process. After S-intestine digestion, the α-glucosidase inhibitory activities of pomace and whole kiwifruit were 1.33 and 3.11 mg acarbose per g FW, respectively. The fermentation of the whole kiwifruit and pomace caused reduction of the pH and variation of the gut microbiota diversity. Compared with whole kiwifruit, the pomace showed stronger modulative effects on the ratio of Firmicutes/Bacteroidetes. These findings provide scientific evidence for the utilization of pomace and whole gold kiwifruit.