Determination of the drying and rehydration kinetics of freeze dried kiwi (Actinidia deliciosa) slices

The aim of this study was to determine the drying and rehydration kinetics of freeze dried kiwi slices. Well-known thin layer drying models (Lewis, Page, Modified Page I, Henderson and Pabis, Modified Henderson and Pabis, Logarithmic, Midilli, Modified Midilli, Two-term, Two-term Exponential, Modified Two-term Exponential, and Wang and Singh) were fitted to the experimental data. A nonlinear regression analysis was used to evaluate the parameters of the selected models using statistical software SPSS 16.0. For the freeze drying process of the kiwi slices, the highest R-2 value (0.997), and the lowest RMSE (0.018) as well as the chi(2) (0.0004) values were obtained from the Two-term Exponential model. The effective moisture diffusivity (D-eff) of the freeze dried kiwi slices was calculated with the Fick's diffusion model as 7.302 x 10(-10) m(2)/s. The rehydration behavior was determined using distilled water at different solid-liquid ratios at room temperature (18 +/- 1 A degrees C) using Peleg's model. The kinetics of the total soluble solid loss was also determined.