Cyclodextrin hydrophobic cavity size directs soy protein thermal stability and gelation behavior

Enhancing thermal stability in high-content soy protein solutions (SPs) is crucial. Cyclodextrins (CDs), with their distinctive hydrophobic cavities, are commonly used as stabilizers in food systems. This study investigates the effects of cyclodextrins with different cavity sizes (α-CD, β-CD, and γ-CD) and preheating on the thermal stability of soy proteins (SPs). The results show that all CDs improved reheating stability, but their effects were cavity-size dependent. Larger cavities enhanced binding to exposed hydrophobic groups and increased electrostatic repulsion; γ-CD reduced surface hydrophobicity from 197.38 to 148.74. CD addition also markedly suppressed gelation by lowering G', delaying gelation, and increasing water mobility, with γ-CD showing the strongest effect. These results identify cavity size as a key structural parameter for CD-mediated stabilization and establish γ-CD as the optimal stabilizer for formulating thermally stable, high-protein soy liquid foods.