Rheological properties of pea protein isolate-amylose/amylopectin mixtures and the application in the high-moisture extruded meat substitutes

The interactions between the protein and starch molecules should play an important role in preparing the pea protein-based meat substitutes with rich meat-like fibrous structure. In this study, the pea protein isolate (PPI) was firstly mixed with the amylose/amylopectin (0:1, 1:2, 1:1, 2:1, 1:0) mixtures at the ratio of 9:1 and then extruded under high moisture condition (58%, w/w). The effects of the rheological properties of PPI-amylose/amylopectin mixtures on the system response parameters (die pressure, torque, and specific mechanical energy) and the final product qualities (the color, texture properties, in vitro digestibility, macro- and micro-structure) were investigated. Results showed that the amylopectin could decrease the apparent viscosity, storage modulus and loss modulus of PPI dispersion. The addition of amylopectin promoted the formation of protein anisotropic structure and improved the fibrous degree of the extrudates. On the other hand, the amylose had no significant effect on the apparent viscosity of PPI dispersion and could not contribute to the protein fibrous structure formation. Furthermore, both the amylose and amylopectin could significantly reduce the die pressure and torque during the high-moisture extrusion processing, which further decreased the color difference (ΔE), hardness, springiness, and chewiness of the extrudates. Overall, it suggested that the amylose/amylopectin mixture with the ratio of 0:1 was advantageous for preparing the pea protein-based meat substitutes with rich fibrous structure.