Elucidating the modulation of oat starch-protein complex molecular structure and starch digestion under microwave field treatment

The effects of microwave (MW) and water bath (WB) treatments on the physicochemical properties and digestibility of oat protein-starch complexes were investigated. The textural and rheological results indicated that the MW treated group exhibited greater hardness, elasticity, and cohesiveness, as well as higher G′, G″, and apparent viscosity. The results of Fourier transform infrared spectroscopy and X-ray diffraction revealed that the rapid heating by MW promoted the formation of hydrogen bonds, more stable double-helix structures, and ordered structures, thereby enhancing starch-protein complex formation. SEM further validated these findings, showing that the gel network structure formed under MW treatment was denser and more stable, which resisted enzymatic hydrolysis. Starch digestion and LOP-CPS kinetic fitting results demonstrated a slower starch digestion rate in the MW treated group. Confocal laser scanning microscope analysis of the starch-protein interactions during digestion revealed that the physical barrier formed around the starch matrix hindered the binding of starch to amylase, making the starch less susceptible to hydrolysis. Therefore, MW treatment enhanced the gel structure of starch-protein complexes while decreasing their digestibility, positioning it as a promising approach for the development of slow-digesting foods.