Improving survivability of Lactobacillus plantarum in alginate-chitosan beads reinforced by Na-tripolyphosphate dual cross-linking

In the present study, Lactobacillus plantarum PTCC 1058 was microencapsulated in Alginate-chitosan blended beads based on ionically dual cross-linking by Na-tripolyphosphate (Na-TPP). The homogenous solution of bacteria and alginate was dripped into the gelling bath of calcium chloride. After 30 min hardening, filtrate beads were transferred into the solution of chitosan. Dual cross-linked gel beads were prepared by employing Na-TPP solution to the chitosan coated beads. Morphology, particle size, alginate-chitosan interaction, characterizing the structure of single and dual cross-linked beads were determined by using scanning electron microscopy SEM, FTIR and XRD analysis. FTIR analysis demonstrated fabrication of the Na-tripolyphosphate dual cross-linked microcapsules. X-ray diffractograms revealed less amorphous nature of Ag/Cs/TPP microcapsules compared to Ag/Cs ones. Survivability of probiotics and swelling behavior of microcapsules were also evaluated under simulated gastrointestinal conditions. Based on the results, the highest viability corresponds to the dual cross-linked beads (by only 1.58 +/- 0.03 log reduction) compared to single cross-linked alginate (2.26 +/- 0.09 log) and chitosan-coated alginate beads (1.78 +/- 0.1 log). Thus, the reinforced microcapsules could be suitable for improving the capsule stability in site-specific delivery applications.