Four-dimensional (4D) food printing of millet-based bakery food products, for achieving a controlled transformation through baking.
The best selected millet-based dough formulation was used to 3D print the modified B2 bomber shape (MBS). The optimised rice-dough-based support structures were 3D printed at slope angles of 10°–80°. Printed constructs and supports are exposed to external thermal stimuli at 160°C for 21 min to induce 4D-assisted shape transformation through baking. The thermal characteristics of the dough were also studied. Post-baking, dimensional changes, bending angles accuracy, volumetric shrinkage, weight loss and shape transformation precision were measured. The final best construct was further characterised for texture profile, colour and proximate analysis.
The accuracy of the bending angle remained consistent for support angles between 30° and 60°. The volumetric shrinkage ratio of rice-based supports was observed to range from 5.4% to 31.2%, indicating that the design plays a crucial role in influencing transformation performance. The 4D shape transformation accuracy result was much improved by the design of the support structure, as it precisely achieved high values between 60° and 10°. Texture, colour and proximate composition studies showed that the final cookies exhibited high shape transformation precision, remaining firm and appealing.
The best support structure angle, between 30° and 60°, ensures a highly stable transformation. That maintains the structural integrity and dimensional fidelity during post-processing. This study provides the concept for manufacturing more intrinsic, structurally stable 4D printed constructs with assisted shape transformation under thermal stimuli.
