MATHEMATICAL MODELING OF THIN-LAYER PINEAPPLE DRYING

The drying kinetics of pineapple was studied, and the model that best describes it was selected. Pineapple slices were dried in a hot-air oven at temperatures of 50, 60 and 70C; microwave power levels of 385, 540 and 700 W, respectively; and under direct sunlight. Drying time decreased with increase in drying temperature and power level. Drying took place entirely in the falling rate-drying period. Seven mathematical models were fitted into the experimental data. The goodness of fit was determined using the coefficient of determination (R-2), reduced chi-square (chi(2)), root mean square error and sum square error. The two-term, parabolic and Page model best explained the hot-air, microwave and sun-drying behavior of the pineapple. The effective moisture diffusivity increased from 6.89 x 10(-10) to 5.1 x 10(-08) m(2)/s while the activation energy was 12.46 KJ/mol for oven drying and 1.54 W/g for microwave drying.