Effect of Extrusion Treatment on the Microstructure and Physicochemical Properties of Corn Flour

Abstract

In order to improve the processing characteristics of corn flour, the effect of twin-screw extrusion on the microstructure and physicochemical properties of corn flour was evaluated under different conditions of moisture content (15%, 18%, 21%, and 24%) and extrusion temperature (100, 120, 140, and 160 ℃). The results showed that after extrusion, the morphology of starch granules was destroyed, resulting in water absorption and swelling of the starch and gel network formation, significantly improving the hydration characteristics, cold paste viscosity and pseudoplasticity of corn flour (P < 0.05). With increasing extrusion temperature or moisture content, the damage degree of starch crystalline zone and double helix structure became more and more serious. At a moisture content of 18% and an extrusion temperature of 120 ℃, the maximum tensile distance of (28.95 ± 0.66) mm was recorded, indicating the strongest pseudoplasticity. Taken collectively, extrusion modification could effectively improve the problem of the difficulty in molding corn flour due to the lack of gluten protein, which will provide a technical basis for the processing of whole corn staple foods.

Keywords

• extrusion treatment; corn flour; tensile properties; structural properties; physical and chemical properties