Innovating protein-based bioinks with sorghum gel for 3D food printing

3D printing with protein-based materials is advancing the food industry, with sorghum, a protein-rich cereal, demonstrating strong potential as a bioink. This study aimed to develop sorghum protein gels for 3D food printing, focusing on their application as a hydrophobic bioink. Key printing parameters, including printing speed (10, 15, and 20 mm/s), protein concentration (15–35% w/w), and nozzle size (0.52, 0.64, and 0.72 mm), were optimized for improved printability. Rheological properties of the inks were characterized before printing, and the 3D-printed structures were analyzed for microstructure, secondary structure, and crystallinity. Gels with protein concentrations of 35% and 15% (w/w) exhibited poor texture and rheological properties, while concentrations of 20–30% (w/w) displayed shear-thinning behavior with high elasticity and recovery, showing superior printability. An optimal printing speed of 20 mm/s improved shape accuracy and minimized fusion defects. The best printability was achieved using a 25% (w/w) protein concentration and a 0.64 mm nozzle size, aligning well with the digital design. Structural analysis, including crystallinity, FTIR, and microstructure evaluation, revealed significant transformations in protein secondary structure and the formation of a gel network from kafirin particles. This study highlights the potential of sorghum protein gels for different applications in the food and pharmaceutical industries, particularly as bioinks for encapsulation or carriers of hydrophobic micronutrients.