Modeling on hot air and infrared thin layers drying of persimmon slices

Drying is one of the preservation techniques in which moisture removal through simultaneous heat and mass transfer occurs. Due to low energy efficiency and prolonged time of hot air drying, the new drying techniques such as infrared, must be employed. In this study, the effects of temperature and drying method on the kinetics of persimmon slices with 5 mm fixed thickness were investigated. The tests were performed at 3 temperature levels (50, 60 and 70◦c) using both hot air and infrared dryers in 3 replicates. The experimental data obtained from drying treatments were fitted to 9 mathematical models in order to evaluate the drying kinetics of persimmon slices. The fitting quality of the proposed models was evaluated using the coefficient of determination (R2), root mean squares error (RMSE), chi- square (χ2) and sum square error (SSE). Based on the results, Wang and Singh model was found to be the best model fitted to the experimental hot air drying data at all temperature levels. In the case of experimental infrared drying data at 50 and 60◦c, the logarithmic model showed the best fitting results while at 70◦C, 2-term model showed the highest fitting quality. These models exhibited the highest value of R2 and the least RMSE, χ2 and SSE comparing to the other models