Natural polymer-based encapsulation system for <i>Lactiplantibacillus plantarum</i> HD51: Enhanced gastrointestinal stability and functional bioactivity

This study developed a natural polymer-based microencapsulation system for <i>Lactiplantibacillus plantarum</i> HD51 using alginate, skimmed milk and flaxseed mucilage. Four formulations were evaluated for encapsulation efficiency, gastrointestinal survivability, release behaviour, exopolysaccharide production, antimicrobial activity, storage stability and pancreatic lipase inhibitory potential. The composite matrix (Alg-SM-FM) achieved the highest encapsulation efficiency (95.54%) and exhibited improved protection of probiotic cells under simulated gastric and intestinal conditions compared with single-component systems. Scanning electron microscopy revealed a denser and more compact microstructure in composite formulations, indicating enhanced physical protection. Encapsulated probiotics maintained viable counts above 10⁷ CFU/g, showed controlled release in simulated intestinal fluid and retained antimicrobial activity and exopolysaccharide-producing capability. Multivariate analysis using principal component analysis revealed clear associations between formulation composition and key functional attributes, including encapsulation efficiency, bead size, survivability and bioactivity. Additionally, encapsulated <i>Lactiplantibacillus plantarum</i> HD51 demonstrated measurable pancreatic lipase inhibitory activity, suggesting potential relevance for metabolic health applications. Overall, the results indicate that combining alginate with dairy- and plant-derived biopolymers provides a promising food-grade strategy for enhancing probiotic stability and functionality in functional food and nutraceutical applications.