Effect of screw speed, temperature and moisture on physicochemical properties of corn gluten meal extrudate.

Background: Corn gluten meal (CGM) is the main by-product of corn starch with rich protein and dietary fiber. The extrusion of CGM with a twin-screw extruder aimed to expand the novel utilization of this plant-protein resource. The impacts of screw speed, extrusion temperature, and material moisture on physicochemical properties of the extrudates were assessed.

Results: The microstructure depicted a favorable fiber-like structure formed under screw speed 120-150 rpm, extrusion temperature 140-150 °C, and material moisture 40-45%. Expansion ratio, rehydration ratio, water solubility index, hardness, and chewiness increased until screw speed reached 120 rpm. With accelerating extrusion temperature, these indicators showed an overall increasing trend. As for material moisture, expansion ratio, hardness, and chewiness showed a decreasing trend. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed that disulfide bonds were necessary for protein crosslinking during extrusion.

Conclusion: It can be concluded that CGM is extrudable, whose textural and physicochemical properties vary as functions of the extruding parameters, providing diversity for its potential applications. © 2023 Society of Chemical Industry.