Effects of extruded corn flour on the gelatinization properties of wheat flour and dough rheological properties

Extruded corn flour (ECF) was prepared from corn flour (CF) by extrusion process. Different gradient ratios (0 %, 5 %, 10 %, 15 %) of CF and ECF were blended with wheat flour, respectively. Effects of ECF and CF on the gelatinization properties of blended flour, and rheological properties and microstructure of wheat dough were investigated, and linear regression equations were established for the gelatinization properties of blended flour and dough rheological properties. Results revealed that 1) the gelatinization viscosities (peak viscosity, valley viscosity, final viscosity), setback value and attenuation value of blended flour significantly increased with the addition of CF, while the opposite trend was noticed with ECF. 2) the cold viscosity of CF-wheat mixture had no significant change with increasing amout of CF, but the cold viscosity of ECF-wheat mixture increased with the increasing amount of ECF. 3) compared with CF, ECF contributed to enhance the adhesiveness and adhesive force of wheat dough, leading to higher dough cohesiveness and internal structure compactness. 4) the flour gelatinization properties were significantly correlated with the dough rheological properties. Cold viscosity, adhesiveness and damping coefficient of dough could be used for predicting the gelatinization properties of blended flour. These results indicated that ECF helped to improve the thermal stability of blended flour, and prevent the starch retrogradation. ECF content of 5% was favorable for improving the quality of wheat dough.