Effects of soybean insoluble dietary fiber and CaCl2 on the structure and properties of low‐moisture extruded products

Abstract BACKGROUND Texturized vegetable protein is currently a leading alternative to animal meat. This study examined the effects of soybean insoluble dietary fiber (SIDF) (0% to 20%) and CaCl 2 (0% to 1%) on the structure and properties of extruded products made from a soybean protein isolate‐wheat gluten (SPI‐WG) composite. RESULTS The study showed that SIDF (4% to 8%) increased the viscosity of extruded products, enhanced their specific mechanical energy, and improved their rehydration rate and tensile strength compared with a control group. The rehydration rate of the extruded products reached a maximum value of 331.67% in the 8% SIDF, 0.5% CaCl 2 groups. The addition of excess SIDF prevented the cross‐linking of protein molecules to form a loose network structure. Analysis of the infrared spectrum and intermolecular forces showed that physical interactions between fibers and proteins were the dominant forces, with hydrophobic interactions and hydrogen bonds primarily maintaining the structure of the extruded products. The addition of CaCl 2 (0.5%) led to protein aggregation and further improved the rehydration and tensile strength of extruded products. CONCLUSION Soybean insoluble dietary fiber can improve the rehydration rate and quality of extruded products. The addition of CaCl 2 mitigated the weakening of the protein structure caused by excess SIDF. These results provide a basis for the improvement of the quality of low‐moisture‐extruded texturized vegetable protein products with a high dietary fiber concentration and a high rehydration rate. © 2024 Society of Chemical Industry.