Effects of Various Sorghum Flour Particle Sizes on the Properties of Sorghum–Wheat Composite Dough Sheets and Noodles

Sorghum flour was milled and fractionated into three particle-size classes, 215–181 µm, 181–96 µm, and <96 µm, then blended with wheat flour at a 30:70 (sorghum:wheat) ratio. The composite flours were evaluated to determine the effects of sorghum particle size on dough-sheet properties and the quality of the resulting noodles. Reducing particle size increased pasting and farinograph parameters, and dough rheological properties improved. The findings indicate that replacing wheat flour with sorghum flour fractions increased gelatinization temperature and gelatinization enthalpy. In addition, the moisture distribution of the dough showed that with the addition of sorghum flour fractions, the closely bound water content of the dough increased. A reduction in particle size led to a significant increase (p < 0.05) in glutenin macropolymer (GMP) content and induced changes in the protein secondary structure of the dough sheets. Noodle quality improved as sorghum particle size decreased, as confirmed by scanning electron microscopy (SEM). Finer particle sizes were associated with lower cooking loss and higher water absorption. Furthermore, the ultra-fine sorghum–wheat composite noodle (WC) attained the highest sensory acceptance after the wheat control (W). Overall, reducing the particle size of sorghum flour markedly improved the functional quality of sorghum–wheat composites. Finer fractions enhanced dough microstructure and gluten network stability, increased thermal stability and pasting robustness, and the resulting noodles exhibited improved cooking performance and sensory scores while retaining favorable texture.