Engineering zein/β-lactoglobulin amyloid fibril complexes stabilized high internal phase Pickering emulsion for controlled delivery of quercetin

High internal phase Pickering emulsions (HIPPEs) stabilized by natural polymers have attracted much attention. However, single zein-stabilized HIPPEs were poorly stable and prone to flocculation near the isoelectric point. In this study, zein was combined with β-lactoglobulin fibrils (β-LGF) via a pH-driven method to construct zein/β-LGF complex nanoparticles (Z/β CNPs) as stabilizers for HIPPEs, then the emulsion was used to deliver quercetin. Our results showed that Z/β CNPs with zein: β-LGF ratios of 4:6 exhibited enhanced colloidal stability at pH 7, which owned reduced particle sizes (<500 nm), lower PDI values, and higher absolute zeta potential. FTIR, XRD, and DSC results confirmed the enhanced intermolecular hydrogen bonding, more ordered structural organization, and increased thermal stability of the complex. The three-phase contact angle of Z/β CNPs (4:6) was 92.3°, which was closest to the ideal value of 90°, indicating optimal wettability for HIPPEs formation. HIPPEs stabilized by Z/β CNPs (4:6) displayed uniform microstructures, strong resistance to coalescence, and high loading capacity for quercetin. Furthermore, the HIPPEs delivery system significantly improved stability and bioaccessibility of quercetin. This study demonstrated that β-LGF could effectively modify zein to produce robust emulsifying nanoparticles capable of forming stable HIPPEs. The findings can improve encapsulation efficiency and offer a highly promising strategy for the delivery of quercetin.