Assessing degree of cook during corn nixtamalization: Impact of processingvariables

Nixtamalization involves cooking and steeping corn in a lime solution, wash ing the corn (nixtamal), and stone grinding nixtamal to form a corn dough o r mesa. Masa is used to produce nixtamalized products (corn tortillas, tort illa chips, corn chips, taco shells, etc.) by forming and baking or deep-fa t frying. The degree of corn kernel cook determines the quality and texture of masa. Response surface methodology (RSM) was used as an experimental de sign 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 (D SC). RSM data exhibited significant (P < 0.005), although not predictive, l inear models for RVA peak viscosity (r(2) = 0.63), setback (r(2) = 0.61), f inal viscosity (r(2) = 0.61), and peak time (r(2) = 0.57), indicating a dep endence of these parameters on nixtamalization conditions. Peak viscosity, setback, and final viscosity increased linearly with steep time. DSC enthal py (r(2) = 0.83) and peak temperature (r(2) = 0.89) of freeze-dried masa al so exhibited significant (P < 0.0001) linear regression models with process ing variables. DSC enthalpy increased with an increase in steep time, sugge sting that starch is annealed during steeping. This study demonstrated that fundamental starch properties were altered on extended steeping during nix tamalization.