Effects of Rice Flour Substitution on the Structure and Processing Characteristics of Mixed Rice-Wheat Dough

Rice contains lysine, which is lacking in general grains, which can make the nutrition more balanced when it is added to cereal foods. Therefore, this study explored the effects of rice flour substitution on the structure and processing properties of mixed rice-wheat dough. With the addition of rice flour (0%–50%), the content of water, fat, protein, amylose, and ash in the mixed flour decreased, while that of total starch and amylopectin increased significantly. The results from the mechanical characteristics indicated that the viscosity disintegration (0.15–0.59 Nm) and β value (0.526–0.716) increased, while the retrogradation value (from 1.15 to 0.69 Nm) and the cooking stability (from 0.92 to 0.73) decreased, revealing that the shear resistance and stability of the mixed flour dough decreased after the addition of rice flour, but its increased gelatinization rate delayed aging and improved the storage characteristics. Moreover, mixed rice-wheat dough mainly underwent elastic deformation, and the addition of rice flour interfered with the formation of gluten network structure. Part of the bound water in the mixed flour dough migrates to free water, which showed that the continuity and uniformity of gluten network structure become worse by competing with wheat gluten for water absorption. When the addition of rice flour was 20%, the dough had the greatest viscoelasticity, micro-structure tensile property and texture, when the addition amount exceeded 30%, the toughness of the dough reduced, which made dough difficult to process. This study provides a theoretical basis for the processing and application of rice flour in staple food in the future.