Ultra‐Fast Infiltration Behavior of Vacuum Freeze‐Dried Apples

ABSTRACT Porous materials display ultra‐fast liquid infiltration arising from the interplay of multi‐scale structures, yet how these hierarchies regulate liquid dynamics and mechanics remain poorly understood. Here, vacuum freeze‐dried (VFD) apples are employed as a bioinspired model to elucidate the structure–infiltration coupling that gives rise to their characteristic “dual‐crispness” texture (a rapid transition from roasted crunchiness to juicy crispness during oral rehydration). In vitro saliva rehydration assays reveal that the ultra‐fast infiltration behavior of VFD apples drives this rapid transformation. Unlike conventional hot air‐dried apples, which undergo structural collapse and yield a monotonous texture, VFD apples feature a synergistic multi‐scale structures—macroporous networks, microcellular cracks, and molecularly exposed hydrophilic groups—that collectively reduce flow resistance, accelerate intercellular infiltration, and enhance saliva capture. This hierarchical coordination rapidly restores cell turgor pressure before swallowing, giving rise to the distinctive “dual‐crispness” sensation. By linking multi‐scale structure to infiltration kinetics, this study establishes generalizable design principles for rapid‐rehydration foods and hydration‐responsive functional materials.