KINETIC-STUDY AND MODELING OF THE DEGRADATION OF THE MAIZE KERNELS QUALITY DURING DRYING IN FLUIDIZED-BED

Only a few kinetic studies have been reported in the literature on the evolution of commercial quality of maize during drying and to the bes t of our knowledge no model allows to predict the dynamic coupling of drying and product quality evolution. The aim of this work is to prese nt new information on the effects of the operating conditions (harvest year, weight of maize to be dried, initial moisture content of the gr ain and air temperature) on the evolution of maize saline-soluble prot ein denaturation and the wet-milling quality during drying of maize in a batch floatation fluidized bed dryer. Also, kinetic laws are propos ed for the quality criteria that will be combined with drying model al ready derived [1,2]. The experimental results show that the degradatio n of the main components of maize (starch and proteins) is considerabl y affected by the temperature level and to a lesser extent by the init ial moisture content of grains. Beyond 70 degrees 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 ab ove 90 degrees C. Kinetic laws derived from this study express the var iation of the degradation rate of proteic and wet milling quality as f unctions of the solubility of saline-soluble proteins or the starch-gl uten separation index, the grain moisture content and temperature.