Printability, microstructure, and flow dynamics of phase-separated edible 3D inks

Personalizing the nutrition and sensorial attributes of 3D printed foods primarily requires various multiscale properties to be individually tailored. Herein, multiscale inks are produced by segregative phase separation, a candidate for further 3D inks texture control, of gellan gum (GG), and whey protein isolate (WPI). The inks microstructure, rheological properties, flow dynamics, their impact on printability, and properties-variables interactions are analyzed using experimental design and clustering. The gels are a GG matrix structured with WPI beads or fibers ranging from <5 to >100 mu m in diameter. A straightforward, six-step printability test determines that high-quality prints require increasing viscosity, which is obtained by reducing the size and length of the WPI beads. Also, flow dynamics and rheology models predict the shear stress and extrusion force, according to the print settings and food-inks fluid properties. The phase-separated inks enable printing at high speed (>25/50 mm/s) upon low extrusion forces (<50 N) and low shear stresses (<500 Pa), according to the calculations and model validation. These printability evaluation methodologies and fabrication of phase-separated inks are particularly interesting for 3D food printing, bioprinting, or biomaterials applications.