A general viscosity model for high moisture extrudates of pea protein isolates/gluten blend.

This article focuses on the rheological characterization of extruded blends of 60% pea protein isolate and 40% gluten to better understand their structuring mechanisms during high moisture extrusion (HME). Using a capillary pre-shearing rheometer, Rheoplast®, the study measured shear and extensional viscosities of samples extruded at varying temperatures (130–150 °C) and moisture contents (50–60% w/w), finding that viscosity followed a power-law behavior without wall slip. The time-temperature superposition principle was extended to incorporate water content effects via the glass transition temperature (Tg), enabling master flow curves to be modeled by the Carreau equation across a wide shear rate range. Morphological analysis by electron microscopy revealed that extrusion temperature influenced fibrous structure, correlating with rheological parameters, and extensional viscosity measurements indicated strong resistance to stretching, which may contribute to fiber formation. These findings provide a rheological model useful for simulating protein blend flow in extrusion dies and offer insights for optimizing plant-based meat analog production.