Effect of Wheat Bran Levels and Particle Size on the Rheological Properties of Wheat Flour Dough

Abstract

This study sheds light on the effects of wheat bran on dough rheological properties, especially gluten index and gassing power. To this end bran with three particle sizes (coarse≥ 300um, medium 300-180um, and fine ≤180um) at three levels (10%, 20%, and 30%) was added to straight-grade flour, which was also used as a control. Proximate analysis, rheological and physical properties of the bran particles and doughs were determined using the approved official methods of Farinograph, Extensograph, Risograph, and gluten index instruments. Farinograph results showed that water absorption capacity (WAC) increased by increasing bran levels, while dough stability decreased by increasing bran particle size. Extensograph results revealed that dough resistance, extensibility, and resistance to extension (R/E) ratio showed a nonlinear behavior between bran levels; and a significant decrease (P≤0.05 ) in resistance value (R50) compared to an increase in the control straight-grade flour (SGF) after 135 minutes of fermentation. Carbon dioxide production using Risograph was significantly (P≤‎ 0.05) higher in the fine bran compared to the other samples after four fermentation times (30, 60, 90, and 120 minutes). There was a significant (P≤0.05) inverse relationship between the gluten index of the dough and the bran particle size.