Microencapsulation of cholic acid via complex coacervation enhances sustained release and antibacterial activity against Escherichia coli

This study aimed to develop a microencapsulated cholic acid (CA) preparation to improve the stability, sustained-release performance, and antibacterial activity of CA for potential use in antibiotic-free animal production. CA microcapsules were prepared by complex coacervation using gelatin and gum arabic as wall materials, and the formulation was optimized by single-factor and orthogonal experimental designs. The optimal preparation conditions were a wall material concentration of 2.5%, a core-to-wall ratio of 1.8:1, and pH 4.1, yielding a drug loading rate of 49.73% and an encapsulation efficiency of 88.76%. The microcapsules showed spherical morphology, low hygroscopicity, improved thermal and storage stability, and a sustained-release profile over 72 h in simulated gastrointestinal media. Both free CA and microencapsulated CA significantly inhibited Escherichia coli growth (p < 0.001), while the microcapsules provided a more prolonged antibacterial effect consistent with controlled release. These findings indicate that complex coacervation is a practical strategy for improving CA performance and support the potential use of CA microcapsules as antimicrobial feed additives in livestock production.