Study of the morphological, structural, thermal, and pasting corn transformation during the traditional nixtamalization process: From corn to tortilla

The changes in the structural, thermal, morphological, and pasting properties of corn were studied along all stages of the nixtamalization process with especial emphasis on the critical points such being the cooking and steeping, wet milling, and baking. Differential scanning calorimetry found an endothermic peak located between 65 and 70 °C that is directly related to the starch gelatinization, and the second exothermic peak about 100 °C that is related mainly to the presence of resistance starch. It was found that corn starch undergoes at least three different gelatinization stage phenomena along the process that provides as a result the changes in its physicochemical properties. One of the most significant findings in this work was the fact that the amount of resistant starch increases with consecutive stages of the process. The quantification of the structural changes that starch undergoes was done by using an X-ray diffraction and pasting profiles. The thermal images of the nixtamal during the wet milling and of the tortilla baking show that the temperature in both cases increases up to the characteristic gelatinization temperature of corn starch and produces a consecutive gelatinization in the starch.