Impact of Extrusion Temperature on In Vitro Digestibility and Pasting Properties of Pea Flour

Pea flour was extruded at 50, 70, and 90 °C. The in vitro digestibility and characteristics of native and extruded pea flour were investigated. The in vitro starch digestibility (IVSD) and in vitro protein digestibility (IVPD) of the extruded pea flour were higher than those of the native pea flour and increased with increasing extrusion temperature from 50 to 90 °C. The rapidly digestible starch increased to 28.34% at 90 °C, the highest slowly digestible starch (SDS) content was 22.70% at 50 °C, and resistant starch content decreased to 4.71% at 90 °C. The IVPD increased from 80.94% relative to the native pea flour to 90.21% at 90 °C. Improved swelling power enabled the extruded pea flour to exhibit better performance and higher breakdown viscosity and lower setback viscosity than the native pea flour demonstrated that extrusion reduced the thermal stability and retrogradation tendency. Increasing extrusion temperatures greatly reduced the relative crystallinity (based on X-ray diffraction analysis) from 32.69% relative to the native pea flour to 9.76% at 90 °C. Extrusion treatment also reduced β-sheet content (based on Fourier transform infrared spectroscopy analysis) from 36.40% relative to the native pea flour to 31.79% at 90 °C. IVPD and IVSD improved, and the SDS content increased at 50 °C and 70 °C, thereby indicating that extruded pea flour can be applied to healthy food products.