Mayonnaise-like high internal phase Pickering emulsions stabilized by co-assembled phosphorylated perilla protein isolate and chitosan for extrusion 3D printing application

In this study, the feasibility of the mayonnaise-like high internal phase Pickering emulsions (HIPPEs) prepared by phosphorylated perilla protein isolate-chitosan composite nanoparticles (LZPI-CS CNPs) as three-dimensional (3D) printing inks and lipid-soluble β-carotene delivery vehicles was explored. The spherical LZPI-CS CNPs (232–336 nm in particle size) were formed by hydrogen bonds and electrostatic interaction, which exhibited improved wettability and superior capacity to reduce interfacial tension and enhance the viscoelasticity of the interfacial film even at low chitosan (CS) concentration. The rigid and dense interfacial architecture formed by LZPI-CS CNPs provided steric barrier and strong electrostatic repulsion, preventing droplets from coalescence during long-term storage, centrifugation and heat treatment. The incorporation of CS also obviously reduced the adsorption percentage of phosphorylated perilla protein isolate (LZPI) at the oil-water interface (from 87.27% to 83.15%), and caused the changes of its secondary structure and tertiary conformation. More interestingly, increasing the CS concentration (0.1–0.6 wt%) in LZPI-CS CNPs led to a progressive strengthening of viscosity, viscoelasticity and thixotropy-recovery capacity of HIPPEs, allowing their controllable injectability and printability during 3D printing. The HIPPEs prepared by LZPI-CS CNPs containing 0.6 wt% CS exhibited the most favorable shape fidelity, printing resolution and clear outline. Additionally, the stability of β-carotene against different environmental stresses was also significantly enhanced after encapsulation with HIPPEs. These findings demonstrated that the complexation of LZPI and CS could provide an effective strategy to construct mayonnaise-like HIPPEs as 3D printing inks and delivery vehicles of hydrophobic bioactive components.