Physicochemical properties and protein structure of extruded corn gluten meal: Implication of temperature

Corn gluten meal is a by-product of corn starch production. To extend its application in the food industry, the extrusion of corn gluten meal was conducted, and the effects of temperature (80, 100, 120, and 140 °C) on physicochemical properties and protein structure of the extrudates were investigated. Corn gluten meal was texturized when the extrusion temperature reached 120 °C, and puffed when it reached 140 °C. With an increment of temperature from 120 to 140 °C, the bulk density, particle size, and zeta-potential of extrudates decreased (from 662.0 to 642.5 mg/cm³, 301.0 to 191.3 nm, and 4.82 to 1.52 mV). SDS-PAGE showed that disulfide bonds and other covalent bonds participated in protein cross-linking during extrusion. Thus, a model of temperature factor on protein reaction for texturization was proposed: With increase of extrusion temperature, the protein peptides got more unfolding; more covalent reactions occurred under higher temperature, which could be important for texturization.