Preparation, characterization, and impact of polysaccharide-zein composite nanoparticles with varied charge properties on the stability of high internal phase Pickering emulsions.

Zein nanoparticles (ZNPs) were prepared via the pH-cycling method and combined with cationic chitosan oligosaccharide (COS), neutral gum arabic (GA), and anionic sodium alginate (SA), forming composite nanoparticles (C-ZNPs, G-ZNPs, S-ZNPs). Polysaccharide complexation enhances ZNPs' hydrophilicity and interfacial adsorption through hydrogen bonding and electrostatic interactions, significantly improving the stability of high internal phase Pickering emulsions (HIPPEs).The charge properties of polysaccharides further influenced the emulsifying behavior: cationic/neutral polysaccharides improved particle dispersibility and wettability, while anionic SA significantly increased surface charge density (absolute zeta potential >45 mV), and electrostatic repulsion, enhancing droplet stability (droplet size <1000 nm) and interfacial adsorption efficiency. At high oil phases (φ ≥ 0.75), all nanoparticle-stabilized PEs exhibited gel-like structures; however, emulsions stabilized by S-ZNPs formed the most compact and elastic interfacial films, demonstrating superior resistance to coalescence during thermal treatment, freeze-thaw cycles, centrifugation (85 % phase retention), and long-term storage (30 d without phase separation). Confocal microscopy and rheological analyses confirmed that the combination of SA's rigid molecular backbone and strong electrostatic affinity with zein enabled the construction of dense, self-healing interfacial networks. This study elucidates the charge-regulated interfacial assembly of polysaccharide-zein nanoparticles, providing insights for designing stable HIPPEs for food delivery, 3D printing, and functional ingredient encapsulation.