30F-1 |
Kinetics of corn flour cooking |
M. P. TOLABA, III1, R. J. Aguerre, III, and C. Suárez. (1) Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, 1428, Argentina The literature about the kinetics of corn cooking is practically limited to corn starch and focused on extrusion conditions. Not much has been done on starch gelatinization in more complex starch system such as, samples of whole cereal grain or cereal flour. The knowledge of the kinetics of starch transitions provides useful information for selecting process conditions. The objective of the work is to evaluate the effect of particle size and water content on the kinetic parameters of starch gelatinization in corn flour. The kinetic parameters values, activation energy, reaction order and pre-exponential factor of the Arrhenius equation, were obtained over the whole gelatinization range assuming gelatinization as two step reaction model. Corn flour samples, with three levels of particle size and water to flour ratios of 1:1, 2:1 and 3:1, were heated from 30°C to 110°C at constant heating rate using a DSC equipment. The Borchardt and Daniels method was used to obtain the kinetic parameters. A RSM method was applied to analyse the effect of experimental factors on kinetic parameters. For the first step of reaction the kinetic parameters were not affected by the experimental factors, The kinetic followed the pseudo-zero order and an activation energy value of 243.6 kJ/mol was obtained. For the second step of reaction, only the activation energy was affected by particle size and water-flour ratio, being the particle size the main effect. The activation energy ranges between 78.1 and 80.7 kJ/mol for the experimental conditions investigated. The mean value of the reaction order was 0.98. The trend of these results seems to be consistent with literature data. This work shows that the non-isothermal method used conducts to reliable kinetic information. It was obtained a polynomial model which describes satisfactory the effects of experimental conditions on kinetic parameters of corn flour cooking.
Session 30F, Food Engineering: Transport processes and kinetics
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