Effect of extrusion on the crystallinity, viscosity, damage starch, and thermal properties of corn flour, masa, and tortilla

Nixtamalized products are very appreciated in México and the world; however, the traditional nixtamalization process (TNP) is highly polluting. Extrusion nixtamalization process (ENP) is an alternative method; however, much research reported high starch damage by ENP that affects the rheology, crystallinity, and general quality of nixtamalized products. This work studies the structural changes of cornstarch exposed to ENP under controlled conditions to produce corn flour, masa, and tortilla. The results of ENP and TNP showed significant differences (p<0.05) for corn flour and masa with higher damage starch in extruded products, but they did not show significant differences (p<0.05) in tortillas. The X-ray diffraction patterns of the native starch granules were modified into an amorphous state when tortillas were produced, also similar preferential crystal growth at the final product: tortilla was observed for both processes ENP and TNP. In addition, the viscosity was similar in the tortillas from ENP and TNP respectively. ENP in proposed conditions is an effective, and non-contaminant technology to produce tortillas with similar characteristic to TNP in the crystallinity, damaged starch, and viscosity.