NaCl mediated physicochemical and structural changes of textured wheat gluten

Abstract The study focused on the effect of different concentrations of sodium chloride (0%, 0.5%, 1%, 3%, 5%, and 10%; NaCl) on the physicochemical and structural properties, including texture properties, protein polymerization, rheological properties and morphology formation, of extruded wheat gluten. The hardness, chewiness, and resilience of the extrudates were increased by NaCl. The highest value of the degree of texturization was obtained at 3%, but decreased at 5% and 10%. The extrudates exhibited lower bulk density and darker colour when NaCl was added. The sodium dodecyl sulfate (SDS)-soluble protein polymers exhibited a similar trend and the lowest value was obtained at 3% addition, which indicated the highest degree of aggregation. The addition of NaCl (0.5%–3%) showed positive effect on the oxidation of sulfhydryl groups to disulfide bonds. The content of β-sheets showed an increase tendency at 0.5%–3% NaCl addition. The addition of NaCl increased the storage and loss modulus in wheat gluten dough while decreasing that of the extrudates. Microstructure analysis by light microscopy and SEM confirmed that the fibrous structure was enhanced with increasing levels of NaCl, and the 3% treatment showed the best, but that collapsed at 5% and 10% NaCl concentrations.