Structural characterization and in vitro antioxidant and hypoglycemic activities of degraded polysaccharides from sweet corncob

Polysaccharides have received increasing attention due to their bioactivity. Sweet corncob is a subsidiary agricultural product, not widely utilized. Previous studies successfully isolated polysaccharides from sweet corncob (SCP). However, the large molecular weight limited their function. In the present study, degraded SCP with four different β-amylase concentrations (50, 100, 200, and 300 U/mL) was prepared by an ultrasonic-assisted degradation method and named DSCP1, DSCP2, DSCP3 and DSCP4. The results showed that the molecular weights were markedly reduced. Furthermore, the degraded polysaccharides were analyzed using ultraviolet spectroscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis, X-ray diffraction analysis, Congo red test, scanning electron microscope analysis, and rheological test. It demonstrated minor changes in the glycosidic linkage, but the primary structure was not changed. In addition, the degraded polysaccharides showed better antioxidant and hypoglycemic activities in vitro, and the activity increased in four degraded polysaccharides compared to that of SCP. It can also be easily observed that DSCP3 showed the highest activity. Overall, this is a promising strategy to improve the biological activities of SCP, and DSCP3 can be used as a functional agent as a better antioxidant and glucose-reducing agent.