Survival of bifidobacteria in alginate-chitosan microcapsules with inulin under simulated gastrointestinal conditions

Introduction. Low viability of probiotic microorganisms during gastrointestinal (GI) transit substantially limits the therapeutic efficacy of oral probiotic formulations. Incorporating the prebiotic inulin into the microcapsule matrix and employing different types of hard capsules may further enhance bifidobacterial protection; however, a comprehensive comparison of these factors using a single GI model has not been conducted.

Aim. To evaluate the effect of inulin incorporation into alginate-chitosan microcapsules and the type of hard capsule (gelatin / enteric-coated) on the viability of B. bifidum under simulated GI conditions.

Materials and methods. Six experimental formulations were prepared: microcapsules (alginate + chitosan) without and with inulin, placed in gelatin and enteric-coated capsules, as well as control groups (bifidumbacterin powder in gelatin and enteric-coated capsules). GI simulation was performed according to the State Pharmacopoeia of the Russian Federation (XV edition, General Monograph 1.4.2.0014): acid stage (0.1 M HCl, pH 1.2, 2 h) followed by buffer stage (pH 6.8). Viability was assessed by Colony-Forming Unit (CFU) counting on MRS-5 agar.

Results and discussion. The highest survival rate was observed in the sample "microcapsules with inulin in an enteric-coated capsule". Microcapsules with inulin in a gelatin capsule provided comparable survival. Microcapsules without inulin demonstrated a slight reduction in cell titer (both enteric-coated and gelatin capsules). Bifidumbacterin powder in a gelatin capsule was characterized by a reduction of viable CFU by 2 orders of magnitude, while in an enteric-coated capsule without microencapsulation, survival decreased by 1 lg CFU/capsule.

Conclusion. Alginate-chitosan microencapsulation is the main factor protecting B. bifidum. Incorporation of inulin into the matrix additionally increases survival. The combination of microencapsulation with inulin and an enteric-coated capsule provides maximum protection; however, no statistically significant advantage of the enteric-coated capsule over the gelatin capsule was detected in the context of microencapsulation with inulin (p > 0.05).

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