Fabrication and characterization of a calcium-induced mung bean protein nanofibrils emulsion gel with tailored rheology for 3D food printing.

Protein nanofibrils (PNFs) show superior functional properties over native proteins, making them promising building blocks for advanced food materials. In this study, MPI emulsions display inadequate gelation properties, which cannot satisfy the printability requirements for 3D food fabrication. Mung bean protein isolate nanofibrils (MPNFs) were fabricated by an acid-thermal method (pH 2.0, 90 °C, 11 h), and calcium-induced emulsion gels were developed for extrusion-based 3D food printing. TEM confirmed the formation of worm-like MPNFs. MPNFs-stabilized emulsions formed self-supporting gels with 100 mM Ca2+ upon heating. The optimized emulsion gel exhibited a uniform microstructure, high water-holding capacity (93.29%), and excellent rheological properties (G' ≈ 850 Pa, shear-thinning behavior and successful high-fidelity printing). It enabled high-fidelity 3D printing without collapse. This work provides a feasible strategy for designing plant protein nanofibril-based emulsion gels as edible inks for personalized food manufacturing.