Microwave-Ca2+ regulation of 3D-printed corn starch-gelatin emulsion-filled gels: Multifunctional effects on printability, dysphagia diets, and β-carotene bioaccessibility.

This study evaluated microwave (MW) heating combined with calcium chloride (CaCl2) in tailoring 3D-printed emulsion-filled gels (EFGs) for improved printability, swallowing-related texture suitability, and β-carotene delivery. The combined MW-Ca2+ treatment was associated with changes in modulus, apparent viscosity, creep recovery, and gel structure. These changes were consistent with contributions from syneresis, ionic cross-linking, hydrophobic interactions, and short-range ordering. The MW-1% sample achieved 89.35% printing fidelity, while all samples met the relevant IDDSI Level 5 and Level 6 texture criteria. During in vitro digestion, differences among infill geometries were associated with β-carotene delivery, with triangle and rectilinear patterns showing better performance than honeycomb. Triangle-filled MW-1% gels showed apparent gastric and intestinal release rates of 17.7% and 38.0%, respectively, and the highest β-carotene bioaccessibility of 64.1%. Overall, this study provided design strategies and theoretical basis for fabricating personalized 3D-printed functional foods, demonstrating how combined material design and 3D printing regulation achieved multiple improvements in printability, swallowing safety, and delivery efficiency.