Abstract:
The effects of phosphorylation, enzymatic treatments, dry heat treatments, and combined treatments on the water absorption index, water solubility index, dispersion time, agglomeration rate, viscosity, particle size, and chrominance of extruded corn flour were analyzed to improve the quality of extruded corn flour. Phosphorylation heat treatments did not significantly affect the viscosity of extruded flour, whereas dry heat treatments by edible gum increased the viscosity. Additionally, enzymatic treatments alone and in combination with phosphorylation and dry heat treatments significantly reduced the water absorption index and viscosity. Specifically, the water solubility index of the flour after enzymatic treatments and combined treatments was greater than that after phosphorylation and dry heat treatments. The water solubility index of the extruded corn flour treated with α-amylase increased from 30.4% to 80.98%, whereas the water absorption index decreased from 4.96 to 1.21. The agglomeration rates of extruded corn flour treated with xanthan gum combined with α-amylase and α-amylase combined with sodium orthophosphate were 1.63% and 1.46%, respectively. These values are lower than those after treatments by sodium orthophosphate, α-amylase, and neutral protease individually, and dry heat treatment by xanthan gum (5.57%, 5.60%, 6.16%, and 5.58%, respectively). In addition, the viscosity of the two products after the combined treatment methods were 83.33 and 100 mPa•s, suggesting that the fluid was relatively thin. Samples subjected to dry heat treatments with sodium orthophosphate and xanthan gum showed viscosities of 2243.33 and 306.33 mPa•s, respectively. The viscosity and agglomeration rate of extruded corn flour treated with sodium orthophosphate combined with neutral protease were 546.67 mPa•s and 4.89%, respectively. The viscosity was moderate, and the agglomeration rate was lower than those after single treatments. For this extruded flour, the dispersion time and particle size were 4.81 s and 131.14 μm, respectively, and the resulting fluid was light yellow. Extruded corn flour is more soluble after combined treatment with sodium orthophosphate and neutral protease
