Valorization of Rugulopteryx okamurae-derived sodium alginate for enhanced printability of soy protein-based bioinks...

The use of sodium alginate extracted from the invasive brown seaweed Rugulopteryx okamurae (RO) was considered for enhanced printability of soy protein isolate-based bioinks in extrusion 3D printing. Valorising the abundant RO biomass into RO-derived alginate (SA RO) offers a sustainable solution to mitigate its severe ecological and economic impact. We compared the performance of bioinks formulated with SA RO against those with commercial alginate (SA) through rheological characterization, printability analysis, and post-printing stability tests. Both alginate types significantly improved the shear-thinning properties of the bioink, which are crucial for successful extrusion. The optimal concentration was identified as 7.5 % for both SA and SA RO, providing adequate self-supporting ability. At this concentration, the bioinks exhibited an apparent viscosity of approximately 2420 Pa·s at a shear rate of 0.1 s^-1, and the printed samples showed high structural fidelity, with a Printability Index closer to the unity. The SA RO displayed comparable performance to commercial SA, demonstrating its high potential as a sustainable, functional biopolymer for developing high-precision food-grade 3D printing inks.