Preparation, Characterization, and in Vitro Digestive Properties of Phosphorylated Chicory Polysaccharide-Iron Complexes

This study employed response surface methodology to optimize the preparation process of phosphorylated chicory polysaccharide iron. It characterized the structure of the composite using Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Through simulated artificial gastrointestinal fluid digestion experiments, sucrase hydrolysis experiments, and mucin-binding capacity assays, the in vitro digestive characteristics of phosphorylated chicory polysaccharide iron were systematically analyzed. The results indicated that the optimal reaction conditions were a reaction time of 1.1 h, a reaction temperature of 64 ℃, and a pH of 10. Under these conditions, the iron content of the prepared phosphorylated chicory polysaccharide iron reached 26.97%±0.25%. Infrared spectroscopy of phosphorized chicory polysaccharide iron showed that the O-H and C=O groups in the phosphorized chicory polysaccharide coordinate with Fe³⁺. XPS confirmed that iron was introduced into the phosphorized polysaccharide in the trivalent state (Fe³⁺). SEM observation revealed that the composite morphology was a dense layered structure. In vitro gastrointestinal digestion results showed that the iron retention rate in gastric fluid was >97% after 24 hours, while in the simulated intestinal environment containing mucin and sucrase, 59% was released after 7 hours, with a cumulative release rate of 74.5%±0.5% after 24 hours. This study provides a theoretical basis for the high-value utilization of chicory polysaccharide resources and the development of polysaccharide iron supplements.