Use of exponential, Page's and diffusional models to simulate the drying kinetics of kiwi fruit

The usefulness of three different mathematical models to simulate the drying kinetics of kiwi fruits has been evaluated: two empirical models, the exponential and the Page models, and a diffusional model solved by the separation of variables method. Drying characteristics of kiwi fruit were examined for average moisture contents from ca. 4.65 to 0.15 kg water/kg dm using heated air for the temperature range of 30-90 °C. Drying kinetics exhibited only one falling rate period. Air temperature affected the drying curves decreasing the drying time of samples. The Page model provided the best simulation of the drying curves of kiwi (average %var = 99.6 ± 0.2%) whereas the exponential model provided the less satisfactory simulation (average %var = 98.0 ± 1.4%). However, only the diffusional model allowed an adequate simulation of the experiments carried out under different conditions of temperature and sample geometry to those used in the identification of the models parameters.