Publication no. C-1999-1004-05R |  VIEW ARTICLE

Assessing Degree of Cook During Corn Nixtamalization: Impact of Processing Variables (1).

D. Sahai (2), J. P. Mua (2), I. Surjewan (2), M. O. Buendia (3), M. Rowe (3), and D. S. Jackson (4,5). (1) Journal Series No. 12543, Agricultural Research Division, Institute of Agriculture and Natural Resources, University of Nebraska-Lincoln. (2) Postoctoral research associates, University of Nebraska-Lincoln. (3) Research technicians, University of Nebraska-Lincoln. (4) Associate professor, Cereal/Oilseed Science and Technology Laboratory, Dept. of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE. (5) Corresponding author. Phone: 402-472-2814. Fax: 402-472-1693. E-mail: <djackson@unlnotes.unl.edu> Cereal Chem. 76(6):850-854. Accepted August 25, 1999. Copyright 1999 American Association of Cereal Chemists, Inc.

Nixtamalization involves cooking and steeping corn in a lime solution, washing the corn (nixtamal), and stone grinding nixtamal to form a corn dough or masa. Masa is used to produce nixtamalized products (corn tortillas, tortilla chips, corn chips, taco shells, etc.) by forming and baking or deep-fat frying. The degree of corn kernel cook determines the quality and texture of masa. Response surface methodology (RSM) was used as an experimental design to study the impact of process variables (cook temperature, cook time, initial steep temperature, and steep time) on the degree of cook measured using a Rapid Visco Analyser (RVA) and differential scanning calorimetry (DSC). RSM data exhibited significant (P < 0.005), although not predictive, linear models for RVA peak viscosity (r(^2) = 0.63), setback (r(^2) = 0.61), final viscosity (r(^2) = 0.61), and peak time (r(^2) = 0.57), indicating a dependence of these parameters on nixtamalization conditions. Peak viscosity, setback, and final viscosity increased linearly with steep time. DSC enthalpy (r(^2) = 0.83) and peak temperature (r(^2) = 0.89) of freeze-dried masa also exhibited significant (P < 0.0001) linear regression models with processing variables. DSC enthalpy increased with an increase in steep time, suggesting that starch is annealed during steeping. This study demonstrated that fundamental starch properties were altered on extended steeping during nixtamalization.