Enhanced 3D printing performance of fish gelatin/oxidized agarose stabilized emulsion gels: Rheological and...

Fish gelatin (FG)-stabilized oil-in-water emulsion gels for 3D food printing face the challenge of low printing accuracy. This study aims to address this challenge by developing a novel bio-ink through enzymatic modification with galactose oxidase for preparation of oxidized agarose (OA) to enhance the structural integrity of printed constructs. Micro-structure and low-field nuclear magnetic resonance (LF-NMR) analysis revealed that optimal OA incorporation (8.13-10.00 %) could reduce emulsion droplet aggregation with D₃₂ values of 0.83 μm and 0.78 μm, respectively, and decrease the free water content from 15.6 % to 0.7 % (p < 0.05), indicating enhanced water-binding capacity. Optimal emulsion inks (FG-OA-8.13 % and FG-OA-10.00 %) exhibited good temperature or centrifuge stability and could form emulsion gels following heat/centrifuge induction. Rheological results showed typical solid-dominated viscoelastic behavior, superior self-supporting capability and higher solid-liquid balance for FG-OA-8.13 % and FG-OA-10.00 %, exhibiting their great potential of 3D printing. Notably, FG-OA-8.13 % 3D prints achieved 98.7 % printing dimensional accuracy with a maximum hardness value of 90.24 N after solidification at room temperature for 24 h, in contrast to 83.5 % printing stability of 3D prints at excessive OA (>10 %). These findings demonstrate a structure-function relationship between OA-mediated network reinforcement and 3D printing performance, providing a sustainable strategy for developing precision-tailored food-grade bio-inks.