Pea protein-xanthan gum interaction driving the development of 3D printed dysphagia diet

With a rapid ageing population, there is an increasing need for the dysphagia diet because of the chewing/swallowing difficulty suffered by the elderly. 3D printing is able to create appetitive and attractive dysphagia diet. We investigated the potential to develop appealing pea protein isolate (PPI) based dysphagia diet using 3D printing by incorporating xanthan gum (XG) at rates of 0.05, 0.1, 0.3, 0.5, 0.7 and 1% (w/w). Their interaction was investigated by scanning electron microscope (SEM), confocal laser scanning microscope (CLSM), Fourier transform infrared (FTIR), and low-field nuclear magnetic resonance (LF-NMR). Rheological properties and 3D printing behavior were also correlated. The 3D printed product was evaluated through International Dysphagia Diet Standardization Initiative (IDDSI) and chewing/swallowing sensory test. Results indicated that, at a relatively small amount of XG addition (0.05, 0.1 and 0.3%), a relatively uniform microstructure was formed with improved mechanical strength (Yield stress, elastic modulus (G′), and viscosity). Further increase in XG addition (0.7 and 1.0%) resulted in an increase in thermodynamic incompatibility between PPI and XG, causing a phase separation and polymer aggregation, which ultimately decreased the mechanical strength of inks. FTIR indicated that the addition of XG increased PPI β-pleated sheet and β-turn, and decreased the contents of random coil and antiparallel β-sheet. XG-0.3% samples demonstrated high printing precision with great self-supporting capability, smooth surface texture and great sensory evaluation, which could be classified as level 4-pureed/extremely thick dysphagia diet. This work provides insights for the development of visually appealing dysphagia diet using 3D printing.