Oil‐type modulation of the interfacial adsorption behavior of flavonoid‐modified walnut protein hydrolysates to improve the storage stability of high internal phase Pickering emulsions

BACKGROUND: Currently, protein-polyphenol complexes have garnered increasing attention as surface-active substances in high internal phase Pickering emulsions (HIPPEs). However, the effects of the oil type and flavonoid structure on the HIPPE-stabilizing ability of protein-polyphenol complexes remain unclear. Notably, very few studies have investigated the impacts and mechanisms of different oils (olive, flaxseed, and coconut oils) and the effects of the addition of flavonoids (catechin and quercetin) on the interfacial behavior of walnut protein hydrolysates (WPHs) and the co-oxidation of protein-lipid in the resulting emulsion during storage. RESULTS: Incorporating flavonoids was found to reduce the particle size and enhance WPH emulsification efficiency. Compared with catechin, quercetin demonstrated a greater affinity for adsorption at the oil-water interface, thereby improving the interfacial adsorption properties of WPHs across all the oil phases, although the oil type influenced the concentration of flavonoids at the interface. Excessive WPH-quercetin complex nanoparticles can form a dense multilayer at the interface and compactly pack oil droplets, endowing HIPPEs with higher viscoelasticity, greater storage stability, and stronger protection against lipid and protein oxidation than other WPH-based HIPPEs do, especially in cases of olive oil-HIPPEs. CONCLUSIONS: Our results demonstrated that the interfacial structure of WPH-flavonoid complexes play a major role in the emulsion stabilization efficiency, followed by the type of oil. © 2024 Society of Chemical Industry.