Evaluation of chitosan hydrochloride-alginate as enteric micro-probiotic-carrier with dual protective barriers

In this study, the cells-free and cells-loaded chitosan hydrochloride-alginate (CHC-Alg) microcapsules were firstly fabricated with polyelectrolyte complexes via an orifice-polymerization method. Scanning electron microscope images showed that the CHC-Alg microcapsules had a typical shell-core structure and the model probiotic cells (Bacillus licheniformis) were embedded in the core in cells-loaded microcapsules. The microcapsules prepared had good thermal stability and moisture property (3.89%). Cells survival and release studies showed that the number of probiotic cells released from the cells-loaded microcapsules (approx. 6.36 log CFU ml−1) was 6.19 log CFU ml−1 when they were performed in the simulated gastric fluid (SGF, pH 2.0) for 1 h and subsequently in the simulated intestinal fluid (SIF, 0.3%) for 4 h. The CHC-Alg microcapsules with favorable swelling performances were helpful to permeate the harsh acid to protect the cells in the SGF (pH 2.0). The CHC-Alg microcapsules effectively protected the model probiotic cells, which was attributed to the “dual protective barriers” of the shell-core structure, that is, the primary barrier of the Alg hydrogel layer formed with a compact polymer matrix and the secondary barrier of the PEC film formed on the surface. The microcapsules prepared could be used as an enteric micro-probiotic-carrier for designing potential probiotic delivery systems.