Hardness targeted design and modulation of food textures in the elastic-regime using 3D printing of closed-cell foams in point lattice systems

Recently, 3D printing has become an innovative technique in the structuring and modulation of food textures. The objective is to systematically extended 3D food printing to allow the production of cellular structures with specifically targeted textural properties. This study presents an approach for 3D printing structures with predefined hardness. As a step in the foundation of textural design, parameter fitting of 3D printed foams and finite element simulations was used to obtain a generalized hardness design formula for the 3D printing of closed-cell foams. Structures incorporating spherical bubbles arranged in point lattice cubic configurations were printed at different porosity levels. A complete 3D printing-stabilization method was applied with an integrated on-board layer-based heating and optimized for targeting heat induced material transitions to actively modulate the material's mechanical properties. FEM simulations were performed at different Young's moduli adjusted using variable heating speeds where the results showed an independency of hardness on the foam configuration and the distance between the closed-cell bubbles. Comparable hardness results were observed between the 3D printed and simulated samples where the same exponential decrease behavior was achieved. The hardness design formula was developed in relation to the material's Young's modulus, porosity, and printed geometry. The performance of the obtained relation showed comparable results to the FEM simulations and the 3D printed structures.