Thiolated modified pectin for the efficient encapsulation of Companilactobacillus crustorum MN047

Abstract

Thiolated polymers were synthesized and applied for the encapsulation of probiotics. Thiolated modified pectins (LMP-SH1, LMP-SH2, and LMP-SH3) were synthesized with different additions of l-cysteine (0.3, 0.6, and 0.9 M) to low methoxyl pectin (LMP) according to the determination of the free thiol group. FT-IR, NMR, XRD, and SEM were used to characterize and verify the successful modification of thiolated modified pectins. The molecular weight of thiolated modified pectin were reduced with the additions of l-cysteine, demonstrating the more homogeneous conformation of LMP-SH polysaccharide formation compared with LMP. Rheological analysis demonstrated that LMP and LMP-SH1 were viscoelastic fluid like properties, and LMP-SH2 and LMP-SH3 were solid-like gel properties. With a high addition of l-cysteine (LMP-SH3), the LMP-SH hydrogel was rapidly formed at a concentration of 5% (w/v), and its resistance to external strains was limited. Thermal stability was demonstrated for LMP-SH2 and LMP-SH3 at concentrations of 4% and 5% (w/v) over a temperature range of 25–80 °C. LMP-SH2 and LMP-SH3 hydrogels were applied to encapsulate the probiotic with high encapsulation efficiency (95.67 ± 1.22 to 99.54 ± 0.45%) and desirable protective ability (more than 80% of the survival rate of hydrogel) in the simulated gastrointestinal environment. These results demonstrated LMP-SH could be a good candidate for polysaccharide modification strategy, and the LMP-SH hydrogel could be a good design for probiotic encapsulation system.