Encapsulation of Pediococcus acidilactici in Sodium Alginate-Calcium Lactate-Skim Milk Gel Beads: Characterization...

This study aimed to develop a composite hydrogel matrix of sodium alginate (SA) and skim milk for encapsulating Pediococcus acidilactici CCFM18 and exploring the synergy of these components on protecting the activity and stability of P. acidilactici CCFM18. The synthesis process was optimized using response surface methodology, yielding optimal conditions: calcium lactate (CL) concentration of 4.18% (w/v), curing time of 47 min, and curing temperature of 41°C. The resulting gel beads achieved an encapsulation efficiency of 72.14%, featuring a spherical structure with abundant internal voids. The formation of SA-CL-skim milk gel beads involved cross-linking and hydrogen bonding between the carboxyl groups of SA, Ca²⁺, and the carboxyl groups/hydroxyl groups of proteins, significantly modifying functional group distributions, x-ray diffraction patterns, rheological behavior, and thermodynamic properties. In vitro simulated digestion analysis revealed that the gel beads effectively protected bacteria from gastric acidity and successfully delivered them to the intestinal environment, achieving a release rate of 84.19% with a viable cell count of 4.9 × 10⁷ CFU, which was 8-fold higher than that of unencapsulated bacteria. These findings highlighted the potential of SA-CL-skim milk gel beads in protecting P. acidilactici activity and achieving targeted release.