Influence of Food Matrix on the Bioaccessibility of Fruit Polyphenolic Compounds

This study examined the bioaccessibility of polyphenolic compounds originating directly from fruits or from fruit extracts during their digestion conducted in a simulated human digestive tract. The results demonstrated that polyphenols bound to the food matrix are less bioavailable, but the type of food matrix plays an important role. Depending on the raw material, 14 to 58% of polyphenols present in fruit extracts were transferred to the supernatant, while in the case of polyphenols present in fruits, only 5–9% were transferred. Sediments obtained after in vitro digestion at the stomach and duodenum stage of fruit extracts contained virtually no polyphenols and demonstrated negligible antioxidant activity, whereas after digestion of whole fruits, the detected polyphenols constituted 5–44%. The intestinal microbiota were actively involved in the metabolism of polyphenols, mainly anthocyanins and glycosides remaining after the earlier stages of digestion.