The influence mechanism of continuous hot-air drying on the nutritional, microstructure and in-vitro digestibility properties of protein and starch in whole-grain glutinous corn (black pearl) flour

The present work investigated the impact of continuous hot-air drying treatment (CDHT) on the nutritional properties of protein and starch, as well as the microstructure and <i>in-vitro</i> digestion characteristics during corn flour processing. The findings indicate that CDHT significantly decreased both total starch and amylopectin content. Specifically, total starch content was reduced by 19.15 % compared to the control sample, and changes were observed in soluble sugar content and grafting degree. SDS-PAGE analysis suggested that high temperatures led to the Maillard reaction. Furthermore, CDHT resulted in sample darkening, with △E* increasing from 20.83 (control group) to 39.47 (120 °C). CLSM analysis demonstrated that the drying treatment altered the interaction between starch and protein. High drying temperatures improved protein digestibility while decreasing rapidly digestible starch (RDS) by 5.37 % at 120 °C. Antioxidant capacity of <i>in-vitro</i> digestion products of whole-grain glutinous corn flour was significantly influenced by CDHT temperatures.