O-carboxymethyl Chitosan-coated Bionanocomposite to Enhance Probiotic Viability under Gastrointestinal Digestion, Storage and Heat Treatment Conditions

Background and Objective: Improving probiotics viability in digestive and storage conditions is challenging for the food and pharmaceutical industries. The present study aimed to increase viability of the microencapsulated probiotic strain of Lactobacillus reuteri ATCC 23272 in Ocarboxymethyl chitosan-coated bionanocomposite. The O-carboxymethyl chitosan was used to coat bionanocomposite containing prebiotics of pectin and inulin in presence of magnesium oxide nanoparticles. Material and Methods: Pectin and inulin were used as prebiotics with magnesium oxide nanoparticles to improve the microgel structure and O-carboxymethyl chitosan for coating the microcapsules for increasing viability and stability of the probiotics. The extrusion efficiency, viability after microwave oven drying, survival in the simulated digestive fluids, viability after heat treatment and survival rate in long-term storage at 4 and 25 degrees C after 42 d were analyzed. Optimization of inulin, pectin and O-carboxymethyl chitosan in O-carboxymethyl chitosancoated alginate-based bionanocomposite was achieved using Design-Expert software and simplex lattice mixture design. Results and Conclusion: Optimal formulation was achieved using O-carboxymethyl chitosan coating polymer (68% w/v), inulin (29.4% w/v) and pectin (2.6% w/v) with magnesium oxide nanoparticles at a constant concentration. Results showed microencapsulation efficiency (96.43%), survival after microwave oven drying (99.45%) and survival in simulated gastrointestinal conditions (88.95%). Probiotic viability entrapped in O-carboxymethyl chitosancoated microcapsules decreased by 1.46 log CFU.g-1 at 80 degrees C for 5 min. Moreover, Ocarboxymethyl chitosan-coated bionanocomposite improved the stability of probiotics by 2.93 and 3.25 log CFU.g-1 at 4 and 25 degrees C after 42 d, compared to alginate beads. Additionally, it was observed that O-carboxymethyl chitosan coating enhanced the stability of probiotics entrapped in bionanocomposite beads. Results demonstrated that O-carboxymethyl chitosan-coated bionanocomposite, as a novel microencapsulation, could significantly increase the shelf life and viability of Lactobacillus reuteri in various harsh conditions, compared to alginate beads.