Investigations on the Forming Mechanism of High-Moisture Extruded Fish Noodles Based on Computational Fluid Dynamics Simulation

High-moisture extrusion technology could improve the added value of fish products. This study explored the forming mechanism of fish noodles in a twin-screw extrusion process by computational fluid dynamics (CFD) simulation and detecting the structural information of the raw material during the extrusion process. The results showed that the screw mainly functioned as a conveyor in the transport and cooking zones, and the disordered degree of protein structure increased, with hydrophobic interactions acting as the primary chemical forces. However, as the material entered the mixing zone, the fluid did a turbulent motion, resulting in the formation of a significant number of disulfide bonds. The fibrillated structure of materials was generated in the forming zone, and disulfide bonds were the predominant chemical bonds. During the chilling process, some hydrogen bonds were restored, and the protein structure was gradually organized, eventually forming the shape of fish noodles. This provided the theoretical foundation to fully understand the high-moisture surimi state during the extrusion process and the development of protein-based food.