Empirical Modeling of Extrusion Cooking of Chickpea Flour for Process Scale Up

Abstract

System variables such as specific mechanical energy (SME), pressure before the die (P) and nettorque (T) are important system variables in extrusion cooking. These parameters reflect the combined effect ofmachine parameters (screw speed, L/D ratio, compression ratio, screw configuration, temperature profile alongthe length of the barrel section and feed rate) and feed properties (;food micronutrients; particle size and moisture content of the feed) on system performance which are often used as parameters for scale-upoperations to large capacity commercial applications. Our laboratory scale extrusion experiments with chickpeaflour showed that the system variables, specific mechanical energy (SME), pressure (P) and net torque, werehighly correlated with the process variables die temperature and moisture content of the feed. System variableswere further correlated with extrudate characteristics such as expansion ratio, in vitro protein digestibility, wateractivity, moisture content of extrudate and color. The result indicated that expansion ratio, IVPD and moisturecontent were highly correlated with SME and P with coefficient of correlation above 0.85. Water activity andcolor were also correlated with system variables with coefficients of 0.75 and 0.65, respectively. The resultsshow promise for using system variables for effective control and scale up of large capacity commercialextruders to replicate production of newer products developed in laboratory.