Effects of Screw Speed and Sesame Cake Level on Optimal Operation Conditions of Expanded Corn Grits Extrudates

Mixtures of sesame cake (0-20%) and corn grits processed in a single-screw extruder to improve the nutritional value of corn-expanded extrudates. Response surface methodology (RSM) was used to analyse the effect of screw speed (X1) and sesame cake level (X2) on the objective (radial expansion ratio (Y1), hardness (Y2), degree of gelatinization (Y3), and water solubility index (Y4)) attributes of a corn-based sesame cake extrudates. The optimum acceptable regions determined from subjective decision and previous studies by referred authors. Therefore, it assumed that radial expansion ratio should be more than 4, hardness should be less than 7.7 kgf, degree of gelatinization should be more than 69%, and water solubility index should be less than 2.9%. Individual contour plots of the different responses were overlaid, and regions meeting the optimum radial expansion ratio of 4.03, hardness of 7.51 (kgf), degree of gelatinization of 69.28(%), and water solubility index of 2.87 (%) were identified at the screw speed of 311 rpm and the sesame cake level of 16%, respectively.