Theoretical and experimental analysis of the drying kinetics of bananas Original Research Article

This work reports a theoretical and experimental study on the drying kinetics of bananas, under different air drying conditions. The experimental data of moisture content during drying were treated according to a diffusional model considering constant diffusion coefficient and including successively, through different models, the effects of shrinkage of the fruit and convective mass transfer on its surface. The diffusion and convective coefficients were determined by fitting the model with experimental data, minimising the sum of square residuals, in successive trials. The numerical results, relative to each one of the effects introduced, are compared with experimental data, giving interesting conclusions about the influence of each one of the phenomena considered. The best fitting was obtained when only the convective boundary condition was included in the diffusional model with a constant diffusion coefficient, although this model did not describe the physical phenomena well. Bananas shrink by about 43–47% their original diameter during drying. Therefore, the shrinkage assumption in the model provides greater reliability on the calculated diffusion and convective coefficients.