Effect of Process Variables and Sodium Alginate on Extrusion Behavior of Nixtamalized Corn Grit

Abstract

Corn was nixtamalized and extruded to make instant nixtamalized corn flour for use in the preparation of Mexican alkaline foods like tortillas. Extruded instant nixtamalized corn flour was prepared with the addition of sodium alginate (0, 0.5 and 1%) and a change in process variables (feed moisture 16, 20, 24% and barrel temperature 125, 150, 175°C) using single screw extruder. The extruder die pressure, specific energy consumption (SEC), and extrudate properties such as expansion, water absorption index (WAI), water solubility index (WSI), and viscosity were analyzed. Sodium alginate interacted with various components of the nixtamalized corn and resulted in an increase in die pressure, SEC, WAI, and viscosity of the extruded flour. WSI and expansion of the extrudates decreased with the increase in sodium alginate concentration. Studies on tortillas had shown that the corn masa containing different concentrations of hydrocolloid (sodium alginate) with high water absorption capacity resulted in highest yields and better textural properties. The study could be useful for the tortilla chip industry where a nixtamalized corn flour with high water retention capacity and low water solubility is desired for better quality and textural properties.