Printability and interfacial performance of emulsion gels and bigels in multi-material dual and coaxial food 3D printing

Journal article, 2026

Structured fats like emulsion gels and bigels have emerged as promising animal fat substitutes for plant-based meat analogs. This study investigated the printability, rheological behavior, and interfacial compatibility of emulsion gels and bigels in combination with pea protein isolate (PPI) for extrusion-based single- and multi-material dual and coaxial 3D food printing (3DFP). Rheological analysis confirmed that despite having both systems exhibiting shear-thinning and thixotropic behavior, bigels demonstrate higher mechanical strength (G’ = 1000 Kpa vs 10 Kpa) and structural integrity (yield stress = 500 Pa vs 200 Pa). These properties translated into better print fidelity, with bigels maintaining defined structures across a range of temperatures (30–60 °C) in single-material 3DFP while emulsion gels were prone to phase separation, deformation and collapsing. In multi-material 3DP with PPI, bigels consistently demonstrated clear material separation, forming distinct core-shell structures in coaxial setups as well as maintaining well-defined, evenly distributed phases in dual extrusion. In contrast, emulsion gels exhibited smearing, irregular distribution, and poor interfacial definition in both setups, indicating weaker phase stability and compatibility with the protein matrix. Confocal laser scanning microscopy confirmed better interfacial phase boundaries between bigels and PPI, aligning with rheological and printing outcomes. In conclusion, bigels show high promise as multi-functional structuring agents and fat substitutes in multi-material 3DFP, while emulsion gels require further optimization to enhance their print performance and material compatibility.