Critical Melting–Freezing Pretreatment Enhances Enzymatic Hydrolysis for Porous Starch Preparation: Role of Partial Structural Weakening and Surface Modification

In this study, critical melting followed by freeze-thaw (CMFT) pretreatment was employed as an effective strategy to partially weaken and modify the surface structure of starch, enhancing enzymatic hydrolysis (EH) for porous starch preparation. Compared with EH alone, the CMFT + EH treatment synergistically facilitated porous structure formation while preserving structural integrity. Partial structural weakening and surface modifications induced by CMFT promoted enzyme diffusion into amorphous starch domains, enabling efficient hydrolysis and pore development without excessive granule degradation. CMFT + EH treatment reduced enzyme requirements and hydrolysis time by 33% compared to single enzymatic hydrolysis while markedly increasing water and oil absorption capacities. Porous starch prepared by CMFT + EH exhibited enhanced ordering of double-helical structures, with RC% increasing from 25.48% (native) and 24.74% (enzymatic hydrolysis alone) to approximately 28%. Furthermore, CMFT + EH significantly improved curcumin encapsulation efficiency from 40% (native) to ~88% and increased curcumin stability under various storage conditions. This study provided an effective strategy to enhance enzymatic hydrolysis efficiency for porous starch preparation with reduced enzyme addition and hydrolysis time.