High moisture extrusion of soy protein and wheat gluten blend: An underlying mechanism for the formation of fibrous structures

High moisture extrusion of soy protein concentrate (SPC) and wheat gluten (WG) blends was conducted to investigate the potential use of this mixture in the production of meat analogs. Extrusion samples collected at different zones from the extruder barrel and extrudates were analyzed to determine their texture, microstructure, protein solubility, secondary structure, and mode of disulfide bonds present in the molecular structure. Results obtained from this study indicate that a blend of SPC-WG at 50/50 resulted in the best fibrous structures. In comparison, extrudates prepared by either SPC or WG did not contain any clear fibrous structures. Additionally, hydrogen and disulfide bonds play a major role over extrusion, with a transformation of disulfide bonds from the intramolecular to intermolecular mode. The analysis of the secondary structure shows that the transformation from alpha-helix to beta-sheet and the maintenance of an ideal balance are crucial for the formation of the fiber structure. The extrudate obtained at SPC-WG ratio of 50/50 presented very good rehydration characteristics when immersed in water at 60 degrees C for 40 min, due to WG promoting the formation of fibrous structures.