Abstract: A physically cross-linked hydrogel was constructed by electrostatic interaction between chitosan (CS) and sodium hyaluronate (SH), and its texture properties, microstructure and functional properties were characterized. Meanwhile, the influence of loading with one of the probiotics Lactobacillus rhamnosus and Pediococcus acidilactici on texture characteristics and microstructure of the hydrogel was evaluated, the loading performance was analyzed, and the release mechanism of probiotic-loaded hydrogels in simulated gastroenteric fluid was explored. The results showed that CS-SH hydrogel, which was formed through electrostatic crosslinking, had good texture properties and bacteria-loading properties, and the loading capacity of 0.2 g (dry mass) of hydrogels for L. rhamnosus and P. acidilactici was 1.15 × 109 and 1.25 × 109 CFU, respectively. The probiotic-loaded hydrogel was continuously released in simulated intestinal fluid, and its release mechanism was through surface erosion. The maximum viable counts of L. rhamnosus and P. acidilactici in simulated intestinal fluid were 6.30 and 6.12 (lg(CFU/mL)), respectively. To sum up, CS-SH hydrogel is a potential probiotic delivery carrier that can be continuously released in simulated intestinal fluid. This study provides theoretical guidance and a research basis for the application and mechanism of action of physically crosslinked hydrogels in the field of probiotic loading.

Key words: physically cross-linked hydrogels; chitosan; sodium hyaluronate; bacteria-loading performance; simulated gastrointestinal digestion