Protein-amylose/amylopectin molecular interactions during high-moisture extruded texturization toward plant-based meat substitutes applications

Plant protein-based meat substitutes have generated considerable interest for their benefits in terms of environmental sustainability and personal health. Nevertheless, the meat-like fibrous structures and the tenderness mouthfeel of meat substitutes within processed plant proteins and amylose/amylopectin components remains challenging to generate due in part to the limited control and insight into the extrusion process used to generate these materials. Here, molecular interactions among the proteins and polysaccharides responsible for the formation of tender fibrous structures during extrusion were investigated, using a dead-stop operation. The results suggested that “sub-layer transformation” of protein and amylose/amylopectin molecules occurred at the interface of the die and cooling zone during extrusion, a key step in the process towards the formation of meat-like fibrous structures. The amylopectin promoted unfolding of vicilin and legumin chains in the extrusion die, which favored protein rearrangement in the cooling zone to further promote the formation of meat-like fibrous structures. In contrast, excess phase separation of amylose and protein matrix in the die enhanced self-aggregation and refolding of protein molecules, leading to layered gel-like structures. In total, these observations into mechanistic interactions during extrusion provide improved insight into strategies toward generating meat-like textures in processed plant materials.