Applicability of a single-layer drying model to predict the drying rate of whole figs

In this study the mathematical modelling of single-layer drying of whole (uncut) figs (Ficus carica L. var. tsapela) in an experimental heat pump of closed cycle, is presented. A range of drying air velocities (1.0-5.0 m/s) and temperatures (46.1-60 degrees C) were tested in drying whole (uncut) figs to moisture content below 30% w.b. Drying temperatures higher than 50 degrees C, were lay beyond the operational limits of the specific heat pump and therefore a set of auxiliary electric resistances were used. Seven thin-layer drying models were fitted to drying experimental data of figs, implementing non-linear regression analysis techniques. The statistical analysis concluded that the best model in terms of fitting performance was the Logarithmic one. Correlations between the model parameters and the drying conditions to calculate moisture ratio MR in relation to the drying time, were determined and reported. (c) 2007 Elsevier Ltd. All rights reserved.