High internal phase Pickering emulsions as edible inks for 3D food printing: impact of Hofmeister series ions on their functionality.

This study systematically examined the effects of Hofmeister series anions (CO32-, SO42-, H2PO4-, Cl-, and Br-) on the stability, rheology, and printability of soybean protein microgel-stabilized high-internal-phase Pickering emulsions (HIPPEs). Through multimodal characterization, including light scattering, rheological testing, and confocal microscopy, we demonstrate that anion-specific electrostatic screening and ion binding, driven by size and valence differences, modulate microgel interactions to tune HIPPE properties. The emulsions exhibited robust shear-thinning behavior and structural stability, confirming their suitability as edible inks for 3D printing. Notably, the H2PO4--modified material achieved a printing accuracy of up to 96.07% and demonstrated excellent printability. This study establishes a facile interfacial modification strategy to enhance the performance of HIPPEs as food-grade 3D printing materials.