Post-acid modification-enhanced gelation of casein-tamarind seed polysaccharide-based medium internal phase emulsion and its application in 3D printing.

Printable protein-based medium internal phase emulsions (MIPEs) with low oil fraction have the advantages of reducing the incidence of obesity, coronary heart disease and hypertension. However, the development of printable protein-based MIPEs is still a considerable challenge because reducing oil content will cause phase separation and increase the fluidity of emulsion. In this study, we successfully prepared printable MIPEs (φ = 40 %) inks by co-stabilizing with casein and tamarind seed polysaccharide (TSP) and using post-acid modification technology. Interestingly, compared with pre-acid-treated MIPEs, the G' and viscosity of the post-acid-treated MIPEs were increased by 86.29 % and 78.81 %, respectively. Additionally, with increasing the TSP concentration in the post-acid-treated MIPEs from 0.5 % to 1.5 %, the G' increased from 619.16 to 1381.67 Pa to 804.38-2165.94 Pa. The self-supporting properties and excellent rheological properties desired for 3D printing were achieved by inducing emulsion droplets to form dense structures owing to the synergistical effect of post-acid treatment and high concentration of TSP. This study expands the feasibility of healthy 3D-printed food production.