Integrated numerical simulation and quality attributes of soybean protein isolate extrusion under different screw speeds and combinations

A numerical simulation of the fluid-dynamic parameters (shear rate distribution, shear viscosity distribution and residence time) inside the barrel combined with extrudate properties, is a potential novel approach for investigating molten soybean protein isolate (SPI) under different screw speeds and combinations. Through finite element simulation, computer fluid dynamics and particle tracking simulation analysis, it was found that increasing the screw speed can increase the shear rate, decreased the shear viscosity of the SPI fluid, and reduced the RDT, thereby promoting the dispersion degree. The maximum shear rate and minimum shear viscosity were generated at the screw flight flanks, and the fluid underwent an alternate shearing force in the barrel. A small axial channel width can significantly promote the fluidity of molten proteins. In conclusion, SPI extrudates with a homogenous structure, smooth surface, and favourable colour and textual profile were produced at a relatively high screw speed (140 rpm).