Effects of different exogenous proteins combined with dry heat treatment on physicochemical properties and digestive characteristics of puffed corn flour

Abstract BACKGROUND Puffed corn flour (PCF) is produced by the milling of corn flour, followed by extrusion, puffing, drying and grinding processes. PCF possesses extensive potential applications in the food industry, serving as a raw material to produce diverse expanded foods. Nonetheless, PCF presents certain issues, including inadequate protein content and suboptimal flushing characteristics. A multitude of studies indicate that physical alteration and the incorporation of exogenous protein positively affect the modifications in the physical and chemical properties of starch. This study examined the impact of incorporating exogenous protein alongside dry heat treatment (DHT) on the microstructure, physical and chemical properties and in vitro digestion of PCF. RESULTS Fourier transform infrared spectroscopy results demonstrated that DHT augmented the hydrogen bond strength of the samples while exerting a negligible effect on the overall structure. Furthermore, via DHT, the incorporation of soybean protein isolate (SPI), whey protein isolate (WPI) and egg white protein (EWP) enhanced the water solubility index of the samples by 8.77%, 19.39% and 22.02%, respectively; the resistant starch content increased by 18.12%, 13.28% and 15.56%, respectively. Nonetheless, DHT resulted in a decrease in sample particle size and the formation of additional cracks and pores on the surface of PCF. CONCLUSION The flushing properties of PCF were enhanced by DHT technology and the incorporation of exogenous proteins. The optimal treatment temperature for the EWP group was 90 °C; for the SPI group, it was 80 °C; and for the WPI group, it was 100 °C. © 2025 Society of Chemical Industry.