Effect of xylanase on extruded nixtamalized corn flour and tortilla: Physicochemical and rheological characteristics

Whole white corn was ground, and lime, water and xylanase enzyme (0.05, 0.075 or 0.1% w/w) were added. Blends were extruded, dried and ground to obtain extruded nixtamalized corn flour (ENCF), which was used to make tortillas. The water absorption index and water absorption capacity (WAC) of the corn flours were determined. Viscoelastic characteristics were determined in corn masa made of extruded nixtamalized flours. Tortillas were made, and determination of moisture content and texture (cutting force and rollability) during storage was carried out. Furthermore, tortillas were evaluated by sensory evaluation. The flours containing xylanase showed significantly higher WAC (P < 0.05) than the flour without xylanase. The viscoelastic parameters were increased by adding xylanase, which also decreased the hardening and increased the flexibility of tortillas. Corn tortillas with 0.075 and 0.1% xylanase concentrations were 15% softer than the control (without xylanase). Additionally, corn tortillas made with ENCF containing the xylanase enzyme had acceptable organoleptic characteristics. PRACTICAL APPLICATIONS The extrusion process permits the use of whole corn, lowers processing costs and reduces contaminant effluents (cooking liquor). The addition of the xylanase enzyme during extrusion partially hydrolyzes the main cellular components of the dietary fiber, the arabinoxylans, and modifies its rheological properties. Softening of most corn pericarp layers is essential in forming masa that has acceptable sheeting characteristics, which is important during the tortilla-making process.