Internal structure design for improved shape fidelity and crispness of 3D printed pumpkin-based snacks after freeze-drying

This study aimed to use the internal design of 3D food printing (3DFP) technology to obtain freeze-dried pumpkin with controllable crispness and higher shape fidelity. Two internal structural variables, namely filling pattern (honeycomb, rectilinear, grid, and triangular) and filling rate (25, 50, 75, and 100%), were studied to assess the impact on the shape fidelity and crispness characteristic of the product. As the filling rate decreased, the printing accuracy of the samples increased. Regardless of the filling patterns, the 75% filled samples exhibited the greatest deformation. The crispness of the samples was closely related to the filling pattern and filling rate. In the case of the high filling rate, the internal structure of the samples was dense. It was less likely to be broken under the action of force and the crispness was reduced. In addition, the internal structure of the sample influenced its physical properties, and the crispness customization of the product can be achieved by designing the porosity. Morphological differences between printed and cast samples suggested that 3DFP was beneficial for the processing and preparation of highly viscoelastic materials. The crispness of cast sample was obviously less than that of the 100% filled printed samples. The results opened an interesting perspective to create crisp foods with high shape fidelity that meet specific texture requirements and provide new sensory perceptions.