2001 AACC Annual Meeting Charlotte, North Carolina October 14-18, 2001 Charlotte Convention Center

Corn flour was evaluated by differential scanning calorimetry to determine the kinetic parameters of gelatinization. Corn flour samples with three different particle size and water to flour ratios of 1:1, 2:1 and 3:1, were heated from 30 C to 110 C at heating rate of 12 C/min. The effects of these experimental factors on kinetics parameters were evaluated. The Borchardt and Daniels method was used to obtain the reation order, the activation energy and the pre-exponential factor of Arrhenius equation. This method assumes that the reaction rate is proportional to the ungelatinized fraction, being the reaction order an unknown parameter. The kinetics parameters were obtained by non-linear regression method, assuming gelatinization as two step reaction model. A response surface methodology was applied to analyse the effect of experimental factors on kinetics parameters. The mean activation energy was 243 and 83 kJ/mol for first and second step respectively. Corn flour exhibited pseudo-zero-order reaction kinetics during the first step of reaction. The reaction order follows a pseudo-first order in the second step. The maximum value of the reaction rate increases as particle size decreases. There was no effect of the water: flour ratio observed on the gelatinization kinetics of corn flour.