Texture-modified soy protein foods: 3D printing design and red cabbage effect

Abstract

3D printing can be used to develop texture-modified foodstuffs that are nutritious and appealing to meet the demands of special consumer needs such as those of the elderly with swallowing disorders (dysphagia). In this work, vegetable-containing protein-based food with different internal 3D structures (infill rates of 12.5, 25, and 50%) was elaborated using 3D printing. First, doughs with different soy protein isolate (SPI) content (20, 25 and 30 w/v %) were prepared to select the dough with the most suitable shape fidelity after being printed in an extrusion 3D printer, the dough with 25% SPI (25-SPI) in this case. Then the 25-SPI doughs with 10, 20 and 30 wt % red cabbage (RC) were prepared, and rheologically and physicochemically analysed before printing. All doughs presented a shear thinning behaviour since the viscosity decreased when the shear rate increased, a suitable rheological behaviour for 3D printing. Regarding the effect of RC in the food formulation, viscosity and storage (G′) and loss (G”) moduli increased as RC content increased, with G’ > G” for all doughs, indicating a solid-like behaviour, beneficial to maintain the shape and size of the food sample once it has been printed. 3D printed samples were homogeneous and showed cavities which got reduced gradually as more RC was added to the doughs, as confirmed by SEM analysis. Besides, the texture profile analysis showed that the hardness, gumminess and chewiness of the hydrated samples increased when the infill of the samples increased, while the addition of RC had an opposite minor effect. All food samples were labelled as transitional food, as defined by the International Dysphagia Diet Standardization Initiative (IDDSI) framework.