Preparation of N,O-carboxymethyl chitosan coated alginate microcapsules and their application to Bifidobacterium longum BIOMA 5920

In order to greatly improve vitality of probiotic bacteria within the application, a novel biocompatible vehicle, N,O-carboxymethyl chitosan (NOCs) with appropriate degrees of substitution coat alginate (ALg) microparticles, was prepared by electrostatic droplet generation. The amount of chitosan (Cs) and N,O-carboxymethyl chitosan (NOCs) coated on the ALg microparticles was determined by differential scanning calorimetry. The surface morphology of ALg microparticles, Cs coated ALg microparticles and NOCs coated ALg microparticles was determined using scanning electron microscopy. The coating thickness of Cs coated ALg microparticles and that of NOCs coated ALg microparticles was directly observed with confocal laser scanning microscopy. In order to assess pH sensitivity of microparticles, the bovine serum albumin release from the microspheres was tested in acid solution (pH2.0) for 2h and subsequently in alkaline solution (pH7.0) for 2h. The survival of Bifidobacterium longum BIOMA 5920 loaded in NOCs coated with ALg microparticle was improved in simulated gastric juice (pH2.0, for 2h) compared to that of B. longum BIOMA 5920 loaded in ALg microparticles and Cs coated ALg microparticles. After incubation in simulated intestinal juices (pH7.0, 2h), the release of microencapsulated B. longum BIOMA 5920 was investigated. •Synthesised N,O-carboxymethyl chitosan (NOCs) coated alginate (ALg) microspheres.•Their effect on intestinal microflora was investigated in simulated gastric juices.•NOCs A coated ALg microspheres improved Bifidobacterium longum survival in SGJ.•The modified chitosan layer improved the pH-response of alginate microspheres.•NOCs A coated microspheres could be used to deliver oral bioactive compounds.