Development of quinoa protein-saccharide conjugates stabilized high internal phase Pickering emulsions for 3D printing and β-carotene delivery

High internal phase Pickering emulsions (HIPPEs) exhibit great potential in 3D printing and the delivery of hydrophobic compounds due to their semi-solid rheological properties and high oil phase volume. In this study, quinoa protein-saccharide conjugates were used to stabilize HIPPEs as 3D printing inks for the delivery of β-carotene. The quinoa protein-inulin conjugate (QP-Inu) demonstrated a larger three-phase angle approaching 90°, lower interfacial tension, and a higher absorption rate, resulting in a compact network structure with more tightly packed smaller droplets, as confirmed by particle size and confocal laser scanning microscopy (CLSM) analysis. All HIPPEs exhibited solid-like viscoelasticity and shear-thinning behavior. Among these, QP-Inu stabilized HIPPEs displayed higher viscosity and elasticity, superior thixotropic recovery rates, and enhanced 3D printability with improved accuracy and self-supporting ability. Furthermore, QP-Inu stabilized HIPPEs showed a better encapsulation capacity for β-carotene and superior storage ability, and stability against adverse environmental stresses, including pH, heating, salt ions, and oxidation. In conclusion, quinoa protein-saccharide conjugates can be promising candidates as stabilizers to form food-grade HIPPEs as new 3D printing materials and effective β-carotene delivery system.