Processing and properties of aqueous protein/polysaccharide mixture-based inks for additive manufacturing

Abstract

Three-dimensional (3D) food printing shows its enormous potential in customization of food designs and personalization of nutritional contents. Herein, two aqueous protein/polysaccharide food inks composed of gelatin B (GB)/xanthan gum (XG) and soy protein acid hydrolysate (SP)/XG, respectively, were investigated for material extrusion additive manufacturing. For both ink systems, processing maps were generated based on the relationship between nozzle diameter and XG concentration for different types of printed geometries including filament, 40-layer scaffolds and 3D complex structures (i.e., starfish). XG concentration was found to be strongly linked to ink rheological properties, thus influencing not only the flow behavior during the printing process, but also the shape fidelity and shape retention after deposition. Inks with 3GB/11XG (3 wt% GB/11 wt% XG) and 8SP/15XG (8 wt% SP/15 wt% XG) demonstrated the highest printability. Shape fidelity map for the post-deposition assessment of printed 3D structures proposed the appropriate range of viscoelastic properties through a well-defined shape fidelity index. Texture profile results also revealed that both polysaccharide concentration and protein type are critical to textural properties of the printed objects, guiding the choice of a suitable ink for an individual 3D food printing. Finally, according to the processing and shape fidelity maps previously defined, an 18-layer two-color 3D complex dolphin shape was successfully fabricated using both 3GB/11XG and 8SP/15XG food inks by a multi-material extrusion-based printing technique in one manufacturing process. This work provides comprehensive guidelines to design and fabricate 3D structures of aqueous protein/polysaccharide mixture-based inks to serve the purpose of accurately personalizing and diversifying nutrition for food applications.