Novel carboxymethyl chitosan/N-acetylneuraminic acid hydrogel for the protection of Pediococcus pentosaceus

In this study, carboxymethyl chitosan (CMCS) and N-acetylneuraminic acid (NeuAc) were used to develop C-NeuAc hydrogels to encapsulate Pediococcus pentosaceus QK-1. The mechanical properties, thermal stability, in vitro degradation, and pH sensitivity of the hydrogel were evaluated. The C-NeuAc concentration required for optimal hydrogel performance was 3% (w/v). Hydrogel swelling behaviour was effectively assessed by Fickian diffusion and Schott's second-order kinetic models. The hydrogel demonstrated excellent biocompatibility and low in vitro cytotoxicity. An in vitro assay revealed that the viability of Pediococcus pentosaceus QK-1 in C-NeuAc had decreased by only 1.41 log (CFU/ mL) after exposure to simulated acidic gastric fluid. Moreover, the survival rate of the encapsulated and free Pediococcus pentosaceus QK-1 cells were 80.1% and virtually zero, respectively, after passage through the gastrointestinal tract. It was empirically determined that low temperature and freeze-drying were the ideal condition and method to ensure storage longevity of the hydrogel-encapsulated probiotic. Hence, C-NeuAc hydrogel is highly desirable as a food-grade probiotic delivery vehicle.