Influence of temperature and shear rate during cooling on the rheological and textural properties of pea protein-based meat analogues

Abstract

Pea protein isolate (PPI) is widely used to produce plant-based meat analogues via high-moisture extrusion. Key parameters during extrusion processing such as temperature and shear play critical roles in the structural changes that determine the final product's texture and mechanical properties. However, achieving a fibrous meat-like texture remains challenging. Consequently, this study aims to systematically investigate the effects of cooling die temperature and shear rate during the cooling phase of high-moisture extrusion on the rheological and textural properties of PPI-based meat analogues. A rotating cooling die system was employed to independently control shear rates (0–9.03 s⁻¹) and cooling temperatures (70–90 °C). Texture and rheological analysis were conducted to assess hardness, anisotropy, and viscoelastic characteristics. The findings indicate that higher cooling die temperatures (up to 80 °C) resulted in harder extrudates with higher anisotropy, enhancing fibrous structure formation. Increased shear rates during cooling did not significantly influence the hardness and the anisotropy decreased. Hardness, anisotropy, and elastic modulus increased primarily due to enhanced aggregation via disulfide bonds, while aggregation through non-covalent bonds had a comparatively smaller impact on the mechanical properties. Thermomechanical treatment of PPI at higher moisture contents in a rheometer corroborated these results, with both shear rate and cooling temperature significantly affecting the elasticity. This indicated that predictive insights into the texturization potential of plant-based proteins can be gained under extrusion-like conditions by assessing their rheological properties.