Kinetics of Thermomechanical Destruction of Thiamin During Extrusion Cooking

Maize grits were extrusion cooked in a CM45‐F conical, counter‐rotating twin‐screw extruder, at different barrel temperatures (140–200°C), feed moistures (11.8–14.2% w.b.), feed rates (37–51 kg/h), screw speeds (65–81 rpm), and initial thiamin concentrations (9–93 mg/kg). Residence time distribution was measured by a dye tracer technique. A first‐order rate equation was used to model the reaction kinetics, which allowed the calculation of the destruction rate constant using residence time distribution curves. The k‐values were most dependent on barrel temperature, feed moisture, and screw speed. The destruction rate constant of thiamin during extrusion cooking was a function of product temperature and shear stress.