Textural Properties of Extruded Plant Protein Blends

Blends of corn gluten meal and soy protein concentrate in the ratio of 25:75, 50:50 and 75:25 w/w were made up. The blends at 20, 30 and 40% moisture content (db) were extruded at 145°C through 4.24, 3.0, and 2.12 mm diam dies at screw speeds of 60, 120, and 180 rpm to generate different shear environments. Multiple nonlinear regression analysis was used to develop models of bulk density, puff ratio, water-holding capacity and shear strength as a function of moisture content and shear rate. Shear rate affected the dependent variables most. Cooked and uncooked viscosity and product color were also measured. Electron micrographs confirmed some of the findings.