RSM-optimized co-encapsulation of Lactobacillus brevis LSe and FOS in calcium alginate: enhancing encapsulation efficiency and bacterial growth

This study optimized the co-encapsulation of the probiotic Lactobacillus brevis strain LSe and the prebiotic fructo-oligosaccharide (FOS) in calcium alginate beads using a Central Composite Design (CCD). The statistically derived optimal formulation (3.0% w/v sodium alginate, 1.2% w/v FOS, and 2.0% w/v CaCl₂) achieved high initial and 24-h encapsulation efficiencies of 84.7 ± 2.8% and 99.2 ± 1.2%, respectively. Encapsulated cells showed markedly improved growth in culture medium compared to free cells (OD₆₀₀ = 0.70 vs. 0.15). Under simulated GI conditions, encapsulation maintained high viability at pH 2.0, but survival rates did not significantly differ between encapsulated and free cells in simulated gastric juice, intestinal juice, or bile salt solutions (0.3–1.2% w/v). For this specific strain and formulation, the primary benefits of encapsulation are enhanced initial loading and growth promotion rather than substantial GI protection. Nonetheless, the high encapsulation efficiency and improved growth kinetics support the FOS/alginate system as a promising delivery vehicle for L. brevis LSe in functional foods. This study establishes the first RSM-optimized protocol for this co-encapsulation, providing a reproducible framework for future synbiotic delivery system development.