Effect of cooking time, steeping and lime concentration on starch gelatinization of corn during nixtamalization

White dent corn was nixtamalized under different conditions to evaluate thermal properties using differential scanning calorimetry (DSC), swelling power and solubility. Cooking time was the factor that had the major influence on the behavior of the evaluated parameters as indicated by the analysis of variance. Onset and peak temperatures of gelatinization increased with increasing cooking time while gelatinization enthalpies decreased, indicating that more starch granules were gelatinized. A decrease in the swelling power was also observed at increasing cooking times, but solubility was significantly inhibited only if steeping was allowed. Considering these results, it was assumed that amylose-lipid complexes are being formed during cooking and reorganized during steeping. X-ray studies confirmed the presence of amylose-lipid complexes. Steeping also caused an increment in the peak temperature that seemed to support the hypothesis of recrystallization or annealing occurring during this nixtamalization step. Temperature ranges indicated that in general, lime acted as a factor for structural disorganization.