Multi-scale structural reorganization determines the divergent digestibility of A-, B-, and C-type starches upon conventional cooking

A-, B-, and C-type starches exhibited distinct digestibility after conventional cooking. • Cooking disrupted granular barriers and lamellar structures, enhancing enzyme accessibility. • Multi-scale analyses revealed interactions among granular, lamellar, and molecular structural features. • B-type starch formed V-type complexes, partially compensating for the loss of digestion resistance. • C-type starch may retain localized ordered regions, thereby limiting hydrolysis. Starch digestibility is strongly influenced by crystalline polymorphism and processing conditions, yet comparative studies under practical cooking conditions remain limited. This study investigated the multi-scale structural reorganization and in vitro digestibility of A-, B-, and C-type starches after conventional cooking (boiling at 100 °C for 20 min). Cooking disrupted granule surface barriers and lamellar structures, thereby increasing α-amylase accessibility and content of rapidly digestible starch (RDS) for all samples. Among the cooked starches, A-type starch exhibited the highest hydrolysis rate constant ( k  = 0.294 min −1 ) and lowest resistant starch (RS) retention (27.83%), whereas C-type starch showed the lowest k value (0.230 min −1 ) and highest RS retention (31.25%), indicating greater resistance to enzymatic digestion. Multi-scale analyses using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and solid-state 13 C cross-polarization/magic-angle-spinning nuclear magnetic resonance spectroscopy ( 13 C CP/MAS NMR) revealed that C-type starch may retain partially ordered B-type-associated regions during cooking, while A-type starch undergoes extensive crystalline lattice disruption. B-type starch formed V-type complexes, which may have partially compensated for the cooking-induced loss of digestion resistance. These transformations provide a structural basis for the divergent digestion kinetics of the three polymorphs. The results demonstrate how crystalline polymorphism and cooking interactively regulate starch digestibility and suggest that C-type starch may serve as a low-glycemic index (low-GI) ingredient, whereas A-type starch may be suitable for starch-based formulations designed for rapid digestibility.