Analytical model for variable moisture diffusivity estimation and drying simulation of shrinkable food products

An analytical model based on Fick's second law of diffusion has been developed to both evaluate mass transfer properties and describe drying kinetics of shrinkable food products. The proposed model was validated with experimental drying data of chayote slices (0.6 cm thickness) obtained at air temperatures of 40, 50, 60, and 70 degrees C. In all cases, an excellent agreement was found between experimental drying curves and predicted results (R-2 > 0.9969). As expected, the use of higher drying temperatures increased effective water diffusivities, while no effect was observed on shrinkage evolution of the product (p < 0.05). In addition. diffusivity values were found to decrease along with the moisture content of chayote slices (p < 0.05). Under the described experimental conditions, mean water diffusivities were in the range of 4.44 x 10(-10)-8.60 x 10(-10) m(2)/s. Results demonstrated that the proposed model can be applied for the accurate description of experimental drying curves allowing a reliable estimation of mass transfer properties in shrinkable food products such as chayote. (C) 2011 Elsevier Ltd. All rights reserved.