ABSTRACT

The drying kinetic of food crops (tomato, cooking banana, and okra) was studied using oven drying method at slice thicknesses of 2, 4, 6, and 8mm and temperature of 40, 50, 60 and 70°C. Fick's second law was used to calculate the moisture diffusivity and it was observed from the result that the moisture diffusivity increases with increase in temperature for the three selected food crops. The drying characteristics of the selected food crops were satisfactorily described by Page model. The activation energy "Ea" was determined using Arhhenius equation and the following result was obtained; for cooking banana was determined to be 2.879KJmo1' for 2mm, 3.754KJmoF' for 4mm, 5.53KJmoF' for 6mm and 6.l74KJmoF' for 8mm; for tomatoes, l.454KJmoi' for 2mm, 2.62KJmo1' for 4mm, 3.594KJmol 1for 6mm and 5.606KJmoF' for 8mm and for okra, 1.5957KJmoF1for 2mm, 1.848KJmoF' for 4mm, 4.028KJmoL1for 6mm and 4.905KJmoF' for 8mm, which shows that the activation energy "Ea" increases with increase in slice thickness and temperature and also it was observed that the moisture ratio of the selected food crops decrease rapidly with increase in temperature and increase in drying time. Finally the drying of the selected food crops takes place at the falling rate period.