Effect of different anionic polysaccharides on whey protein's S/O/W bilayer emulsions containing EGCG: Molecular interaction and stability under various environmental stresses

We aimed at investigating the effect of different anionic polysaccharides (pectin, carboxymethylcellulose, and gum Arabic) on the physicochemical properties and stability of whey protein isolate (WPI)- stabilized solid-in-oil-in-water (S/O/W) bilayer emulsions loaded with epigallocatechin gallate (EGCG). S/O/W emulsions were prepared by homogenizing EGCG-loaded oil with an aqueous phase containing WPI and the selected polysaccharides. The emulsions were characterized for their particle size, zeta potential, microstructure, and rheological properties. Results noted that WPI-pectin stabilized emulsions demonstrated the best stability, with the smallest mean particle diameter (0.46 μm), highest zeta potential (−26.13 mV), and improved viscoelastic properties. Most importantly, WPI-pectin stabilized emulsions achieved the highest EGCG encapsulation efficiency (84.50 %) and adsorbed protein content (64.98 %), where their values in WPI-gum and WPI-carboxymethylcellulose were (57.87 and 67.33 %) and (44.57 and 53.22 %), respectively. Molecular docking simulations also provided insights into the interactions between WPI, lecithin, and polysaccharides in the presence of EGCG, elucidating the interfacial layer formation. This study highlights the potential of tailored protein complexes for developing stable delivery systems for polyphenols in functional food and beverage applications.