4D-printing of dough: Shape shifting mechanism of baked dough filaments

Predictable and functional shape morphing during thermal processing remains a central challenge in 4D food printing, largely due to the lack of mechanistic understanding of deformation in concentrated plant-based formulations. Here, we propose a bubble-induced bending mechanism to explain the observed thermo-induced morphing behavior, in which through-thickness heterogeneity in bubble size, volume, and distribution within a high-solids particle-starch matrix is associated with localized curvature. Using a commonly used pea-based formulation as a model system, the results indicate that this mechanism is associated with a link between printing path design and bending direction, enabling predictable and programmable shape transformation. Systematic variations in baking conditions and printing geometries support the generality of the proposed mechanism and its predictive potential. Based on this mechanistic framework, customized edible structures, including printable cutlery and flower-like constructs, are realized under realistic baking conditions, serving as proof-of-concept demonstrations. These findings provide a mechanistic foundation for designing thermoresponsive food architectures and advance the understanding of microstructure-function relationships in concentrated plant-based colloidal systems.