Gellan gum-quercetin covalent complex prepared by the free radical grafting: Characterization, bioaccessibility and intracellular antioxidant activity

To enhance the antioxidant activity and bioaccessibility of quercetin (QU), in this study, the gellan gum (GG) and QU complex was prepared by the free radical grafting method. The covalent bond between GG and QU was confirmed by UV-visible, Fourier transform infrared (FT-IR) spectroscopy and Nuclear magnetic resonance (NMR). FT-IR showed that the GG-QU complex forms a new peak at 1079 cm^-1. Thermal analysis indicated that the GG-QU complex had higher heat resistance. Compared to QU, antioxidant assays showed that the DPPH radical scavenging and reducing power of the GG-QU complex were increased by 59.17 % and 36.93 %, respectively. And the GG-QU complex significantly improved gastric retention and intestinal release of QU. This result suggested the bioaccessibility of GG-QU complex was enhanced. This resulted in higher in intracellular antioxidant activity and better effect on reducing Malondialdehyde (MDA) content. The research provides theoretical support for the construction of high-performance food distribution system.