W1/O/W2 emulsion stabilized by β-lactoglobulin/exopolysaccharides/epigallocatechin gallate complex: Protective effects on Lactobacillus plantarum A81 during storage, pasteurization and gastrointestinal digestion.

Abstract

The efficacy of probiotics is limited by their low survival capacity in human gastrointestinal tract. In this study, a water-in-oil-in-water (W1/O/W2) emulsion delivery system stabilized by a ternary complex composed of β-lactoglobulin (β-LG), exopolysaccharide (EPS) and epigallocatechin gallate (EGCG) was constructed to encapsulate L. plantarum A81. Compared with native β-LG and binary β-LG-EPS complexes, the β-LG-EPS-EGCG ternary complex significantly decreased emulsion droplet size, improved interfacial protein adsorption efficiency, and formed a denser, elastic interfacial structure. Confocal laser scanning microscopy confirmed more uniform droplet distribution and favorable bacterial encapsulation in ternary complex-stabilized emulsions. Furthermore, the emulsion stabilized by β-LG-EPS-EGCG complex significantly improved the survival rate of strains during 30-day storage (from 27.62% ± 1.35% to 47.33% ± 1.23%), after pasteurization (from 10.55% ± 1.24% to 18.87% ± 1.56%), and after in vitro simulated gastrointestinal digestion (from 3.01% ± 0.81% to 8.97% ± 1.37%). These results demonstrate that β-LG-EPS-EGCG ternary complex is a good stabilizer for W1/O/W2 emulsion.