Development of Triple-Polymer Beads for the Delivery of Probiotics under Simulated Gastrointestinal Digestion

This study developed triple polymer beads composed of alginate, inulin and chitosan for encapsulating Bifidobacterium bifidum TISTR 2129 and Lactobacillus sporogenes BC 208. Four formulations were prepared by the extrusion method, representing alginate (A), alginate with chitosan coating (AC), alginate with inulin (AI), and alginate with both inulin and chitosan coating (AIC). The beads were evaluated for encapsulation efficiency, swelling behavior, and probiotic release under simulated gastrointestinal digestion using the INFOGEST protocol. AI and AIC beads exhibited higher encapsulation efficiency (up to 92%) compared to A and AC, suggesting that inulin improved the interaction between the matrix and probiotic cells. All formulations showed contraction in acidic conditions (pH 3), with AI and AIC showing the lowest swelling, indicating a more compact network. In intestinal conditions (pH 7), swelling increased, particularly in A bead. Notably, AIC beads demonstrated the highest probiotic release (7.32 ± 0.03 log CFU/mL) at 10.25 h, despite exhibiting the lowest swelling, indicating a sustained and controlled release. These results confirm that the combination of inulin and chitosan enhances bead stability, encapsulation efficiency, and targeted delivery, supporting the application of triple polymer systems in functional food development.