Effect of Malting and Nixtamalization Processes on the Physicochemical Properties of Instant Extruded Corn Flour and Tortilla Quality

This research aimed to prepare instant flour from malted and raw (un-malted) corn flours nixtamalized by the extrusion process and evaluate the effect on the physicochemical properties of tortillas prepared using these flours. White maize was malted for 24 h, dried at 50 ± 1 °C, and ground. Subsequently, 0.3 % lime and 25 or 30 % water were added to ground malted or un-malted corn, and the mixture was refrigerated (4 °C) for 12 h. These samples were nixtamalized by an extrusion process in a single screw extruder at two temperature profiles within four heating zones, TP1 (60, 60, 70, and 80 °C) and TP2 (60, 70, 80, and 90 °C), to obtain corn flour. Water was added to the extruded corn flours to make a dough, or masa, and the masa was then molded and baked to obtain tortillas. The corn flours were characterized according to their ability to absorb water and viscosity profile (RVA). The firmness and rollability after 2 and 24 h of storage were determined, and a sensory evaluation was conducted. The malted corn flour extruded with a 25 % moisture content and TP2 temperature profile yielded tortillas with the best firmness and rollability. In conclusion, the changes during the malting of corn grain and the nixtamalization by the extrusion process improved the water absorption capacity of flours and textural properties of the tortilla and produced a product with acceptable sensory properties.