Development of emulsion-based edible inks for 3D printing applications: Pickering emulsion gels

Emulsions gels can be used as edible inks for 3D food printing applications because of their tunable composition and viscoelastic properties. Oil-in-water emulsion gels can be created by crosslinking the oil droplets using chemical or physical approaches. For food applications, chemical crosslinking agents are undesirable because they have safety concerns. In this study, Pickering emulsions gels (PEGs) were therefore fabricated by physically crosslinking anionic protein nanoparticle-coated oil droplets with cationic chitosan. Chitosan formed electrostatic bridges between neighboring oil droplets, as well as a network structure in the surrounding aqueous phase. The viscoelastic properties of PEGs could be tuned by adjusting the droplets and chitosan concentrations. These soft materials exhibited physicochemical attributes that made them highly suitable as edible inks for 3D printing applications, including the ability to maintain specific shapes, to form smooth surfaces, and to give a high print fidelity. Moreover, the tribological behavior of these PEGs was similar to that of oil in the mixed and hydrodynamic regimes, indicating that they exhibited good lubrication properties. Overall, this study has demonstrated the suitability of PEGs to be used as edible inks for creating novel food materials by additive manufacturing.