Kinetic Study and Modeling of the Degradation of the Maize Kernels Quality During Drying in Fluidized Bed

Abstract

ABSTRACT Only a few kinetic studies have been reported in the literature on the evolution of comercial quality of maize during drying and to the best of our knowledge no model allows to predict the dynamic coupling of drying and product quality evolution. The aim of this work is to present new information on the effects of the operating conditions (harvest year, weight of maize to be dried, initial moisture content of the grain and air temperature) on the evolution of maize saline-soluble protein denaturation and the wet-milling quality during drying of maize in a batch floatation fluidized bed dryer. Also, kinetic laws are proposed for the quality criteria that will be combined with drying model already derived [1, 2]. The experimental results show that the degradation of the main components of maize (starch and proteins) is considerably affected by the temperature level and to a lesser extent by the initial moisture content of grains. Beyond 70°C, the denaturation of saline-soluble proteins occurs rapidly in the heat-up period of the grains. As for the wet-milling quality degradation, it starts only above 90°C. Kinetic laws derived from this study express the variation of the degradation rate of proteic and wet milling quality as functions of the solubility of saline-soluble proteins or the starch-gluten separation index, the grain moisture content and temperature.