Engineering stable gels: Whey protein isolate microgel-induced complexation with β-cyclodextrin in high internal phase emulsion gel

The demand for innovative and sustainable food structuring technologies has driven significant research into high internal phase Pickering emulsion gels (HIPPEGs) as versatile systems for encapsulation and delivery applications. In this study, we developed high internal phase Pickering emulsion gels (HIPPEGs) stabilized by whey protein isolate microgels (WPIM) complexed with β-cyclodextrin (βCD) for potential applications in 3D food printing. WPIM was prepared through thermal and mechanical treatments, followed by complex formation with βCD at concentrations of 0.5–4.5%. The HIPPEGs, formulated with 75% sunflower oil and 25% aqueous WPIM-βCD dispersions, exhibited enhanced stability and rheological properties. Increasing βCD concentration significantly reduced interfacial tension (from 15.3 to 9.8 mN/m) and contact angle (from 135.3° to 83.2°), indicating improved wettability and interfacial adsorption. Particle size increased (18.2 to 142 μm) with higher βCD and NaCl concentrations, while zeta-potential shifted negatively, enhancing electrostatic repulsion and stability. Rheological analysis demonstrated shear-thinning behavior and increased apparent viscosity (250 to 540 Pa·s) and storage modulus (G') with βCD addition, supporting extrusion and self-supporting characteristics essential for 3D printing. Microscopy revealed uniform droplet encapsulation and a tightly packed structure, minimizing coalescence. Stability tests confirmed structural integrity over 32 days without phase separation. These findings demonstrate that WPIM-βCD-stabilized HIPPEGs possess excellent printability, mechanical strength, and storage stability, offering a scalable approach for designing functional and sustainable 3D-printed food materials.