Effect of microwave treatment on the structure and digestive characteristics of quercetin-added corn starch

The impact of microwave treatment (MT) on corn starch-quercetin complex (CS-Q) is investigated in this study. The results indicate that MT significantly increased the complexation index (CI) of quercetin with corn starch from 36.08 % to 47.73 %. Structural and digestive properties were also investigated. Scanning electron microscopy (SEM) revealed that microwave-treated corn starch-quercetin complex (MT-CS-Q) formed a more compact complex than CS-Q. Fourier-transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) analyses confirmed that MT-CS-Q exhibited a highly ordered structure, with the crystalline conformation of starch transitioning from A-type to A + V-type. Moreover, the dense structure formed by quercetin and starch after microwave treatment significantly reduced the in vitro digestibility of the complex, resistant starch content increased from 11.91 % to 19.06 % compared to the non-microwave treated complex. During simulated gastrointestinal digestion, MT-CS-Q reduced quercetin release in the stomach and increased its absorption in the intestine. These findings demonstrate that microwave treatment is an effective method for enhancing the CI of quercetin with corn starch. The results provide a theoretical basis for the development and utilization of functional starch.