CASSAVA CHIP DRYING BY USING A SMALL-SCALE HOT-AIR MICROWAVE OVEN

Characteristics of cassava microwave hot-air drying were investigated in a 2-planes microwave hot-air dryer. The drying experiments were carried out at two levels of sample surface temperature set-points viz. 70 and 80°C respectively. Cassava (Rayong-9) with 2.5 kg weight and 61 % moisture content on wet basis was dried in the dryer for about 5-5.3 h. It was found that the drying time decreased with an increase in sample-surface temperature set point. Approximately 89 % of the moisture was removed during the drying period. The rapid decrease in moisture ratio values followed by the gradual decline period was found in all experiments. With regard to drying kinetics, 5 commonly used mathematical models were examined with the experimental data. It was found that Page’s and diffusion models provided a good agreement between the experimental and predicted moisture ratio values. The regression results indicated that high values of coefficient of determination and adjusted coefficient of determination as well as low value of standard error of estimation were reported for the case of these two models