Drying Kinetics of Organic Parchment Coffee Beans orgánico usando microondas con lecho fluidizado: modelado semiteórico

The aim of this study was to model the drying kinetics of microwave and fluidised bed of parchment coffee beans (Coffea arabica L.) using a semi-theoretical approach. A completely randomized design with six treatments: three with microwave drying (MD) and the rest with microwave fluidised bed drying (MFBD) was carried out. The drying curves were established until reaching a final moisture content between 10 and 12 % w.b. Results indicated that the drying time decreased as the microwave power level increased. When MFBD was used, drying times increased approximately 4-fold compared to MD treatments. The values of effective diffusivity for coffee beans treated with MD and MFBD ranged from 0.913 to1.72X[10.sup.-9] [m.sup.2].[s.sup.-1] and from 0.23 to 0.42X[10.sup.-9] [m.sup.2].[s.sup.-1], respectively. Although all the models presented high goodness of fit, the two-term model presented the highest [R.sup.2] (>0.98) and lowest RMSE (0.0128-0.0285). In general, all models adequately fit the experimental data, so they can be used to predict the drying kinetics, therefore they could be very useful in equipment design and optimization of the coffee drying process.