In Vitro Effects of Inulin, Resistant Dextrin, and Stachyose on the Functional Properties and Digestibility of Corn Starch

This study explores the effects of three soluble dietary fibers (SDFs)—inulin, resistant dextrin, and stachyose—on the in vitro digestion of corn starch. Incorporation of SDFs significantly influences starch physicochemical properties by reducing swelling power, solubility, pasting viscosity, and breakdown, while increasing pasting temperature and particle size (p < 0.05). During in vitro digestion, the presence of SDFs significantly decreased the rapidly digestible starch (RDS) content and increased the resistant starch (RS) content (p < 0.05). Microscopic observations reveal that SDFs alter the microstructure of starch gels, enhancing the stability of the gel matrix. Fourier-transform infrared (FT-IR) spectroscopy suggests the formation of hydrogen bonds between SDFs and starch. Furthermore, SDFs exhibit glucose adsorption capacity and α-amylase inhibitory activity, highlighting their multiple mechanisms in modulating starch digestion. The differential effects of SDFs depend on their molecular structure and physicochemical properties, such as chain length and hydroxyl group density. These findings offer new insights into the role of SDFs in modulating starch digestion and highlight their potential applications in designing low-glycemic and fiber-enriched functional foods.