Dietary fibre hydrogels: Tunable polydextrose-sodium alginate networks for bioactive compound delivery

Herein, we developed a versatile composite hydrogel by combining two dietary fibres, polydextrose (PDX) and sodium alginate (SA), at varying mass ratios (from 9:1 to 6:4). The microstructure of the prepared hydrogels evolved from an irregular macroporous network to a highly ordered honeycomb-like structure with increasing SA content. Fourier transform infrared spectroscopy and X-ray diffraction analysis revealed that PDX-SA composite hydrogels were formed through ionic cross-linking and hydrogen bonding. The incorporation of SA significantly enhanced the swelling capacity, colloidal stability (indicated by a high negative zeta potential), and water retention capacity (indicated by low syneresis) of the hydrogels while reducing their initial gel strength. The composite hydrogel with a PDX:SA ratio of 6:4 (PDX-SA-4) exhibited optimal overall properties, including a uniform microstructure, high swelling ratio (38.32% at 8 h), and excellent suspension stability (zeta potential: -33.92 mV). Furthermore, anthocyanins (ACNs) were effectively loaded into PDX-SA-4, exhibiting a concentration-dependent release profile in vitro. Notably, in vitro digestion experiments revealed that PDX-SA-ACNs synergistic lipid-regulating hydrogel effectively inhibited lipid digestion. These findings indicate that PDX-SA composite hydrogels, with tunable physicochemical properties, can be used to develop functional foods and delivery systems capable of modulating satiety and inhibiting lipid absorption.