Extruded nixtamalized corn flour for making tortilla: The effect of xylanase on the depolymerization of ferulated arabinoxylans

Arabinoxylans (AXs) are cell wall non-starch polysaccharides of cereal grains and are depolymerized by xylanase affecting the rheological properties of their doughs. In this study, corn was ground and mixed with lime; xylanase (0.075 g/g corn) was diluted with water and added to the mixture to achieve a moisture content of 300 g/kg, and the mixture was extruded to obtain flour for producing tortillas. The water absorption capacity (WAC), water absorption index (WAI), AX content and molecular weight (AXMW) distribution, and ferulic acid (FA) content of the flour were then determined. The texture of the tortillas was assessed, and a sensory evaluation was performed. The flour with xylanase showed higher AX contents (24.1 g/kg dry matter) and smaller AXMW distribution (0.53-506 kDa) than the flour without xylanase. The extruded flour presented an FA content of 0.063-0.068 μg/mg AXs. The addition of xylanase decreased the tortilla firmness by 16-18.6% and had acceptable organoleptic characteristics.