Tea Polyphenols Modulate Gel Properties and Hydrolysis Behavior of Sweet Potato Starch

Tea polyphenols (TPs) were utilized to modulate the gelation and hydrolysis behavior of sweet potato starch (SPS). Results revealed that TPs inhibited starch chain reorganization in the gel system, leading to diminished gel strength and viscoelasticity. Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric Analysis (TGA) confirmed that TPs reduced the ordered rearrangement of starch molecules. The degree of short-range ordering and double-helix structure decreased from 0.87 and 0.77 to 0.84 and 0.73, respectively, and the temperature of the maximal thermal decomposition rate was reduced from 326.66°C to 320.83°C. SEM observations indicated that TPs impeded the formation of an ordered gel network structure in SPS. Additionally, TPs reduced the hydrolysis rate of starch, and the content of resistant starch increased from 23.42% to 27.09%, potentially via inhibitory effects on digestive enzymes. Molecular docking studies further demonstrated that ester catechins were the primary components binding to starch digestive enzymes. This study expands the potential applications of TPs in gel foods and provides a theoretical foundation for controlling starch digestibility. PRACTICAL APPLICATIONS: Tea polyphenols regulate the gel properties and hydrolysis behavior of sweet potato starch while increasing resistant starch content, providing a practical approach for developing high-quality gel-based functional foods beneficial for blood glucose stability.