Rheological and mechanical behavior of milk protein composite gel for extrusion-based 3D food printing

To characterize the rheological and mechanical properties of soft matter for 3D food printing, a milk protein composite gel was prepared by dispersing milk protein concentrate (MPC) into sodium caseinate solution and then its rheological and textural properties were analyzed. The results showed that the milk protein gel containing 400-450 g/L of total protein had the best printing performance, matched the model best and had good fidelity. The low-field nuclear magnetic resonance and frequency sweep data suggested that the inner structure of the protein gel gradually transformed from a tangled state to a three-dimensional structure with increasing total protein content, which is beneficial for 3D printing. The apparent viscosity, thixotropy, and yield stress also increased with the total protein content. Thus, rheology could be used to evaluate the applicability of soft materials for extrusion-based 3D printing. This study provides a potential reference for evaluating other gel-like materials for 3D printing.