Development and characterization of a casein-hyaluronic acid emulsion gel with high water-holding capacity and excellent rheological properties for 3D printing

This study investigates whether the rheological properties and printability of a casein (CAS) emulsion gels could be enhanced by adding hyaluronic acid (HA) for extrusion-based food material 3D printing applications. The results indicated that adding HA significantly changed the conformation of CAS, enhanced its adsorption capacity at the oil droplet interface, and improved its emulsifying properties through electrostatic interaction and steric hindrance effects. In addition, the CAS-HA emulsion gels had better textural properties, water binding abilities and more uniform and compact network structure than the emulsion gels formed by CAS alone due to the enhancement of hydrogen bonding and hydrophobic interactions. Rheological analysis showed that the emulsion gel with 0.08% HA had excellent rheological properties during all three stages of a simulated 3D printing process. Based on examination of the 3D printed products, it was observed that the printed shapes made with a 0.08% HA emulsion gel had the best printing accuracy, and that the material had excellent self-supporting properties. This study helps reveal the rheology and stability mechanisms of a CAS-HA emulsion gels and provides a broad basis for the rapid development of food-based 3D printing materials.