Thin layer drying of peeled longan (Dimocarpus longan Lour.)

Abstract

In this paper, thin layer drying of peeled longan is presented. Thin layer drying of peeled longan was conducted under controlled conditions of temperature and relative humidity. Drying air temperature has great influence on the drying rates of peeled longan and drying time decreases with the increase in drying air temperature. Eight different thin layer drying models were fitted to the experimental data of peeled longan. The drying parameters of peeled longan were function of air temperature and relative humidity. Page model was found to be the best and Two-term model was found to be next to the best. The agreement between the predicted and experimental values for Page model is excellent. The predictions of Page model, Two-term model and modified Henderson and Pabis model were very close. Either one of these three can be used to provide design data and for simulation and optimization of the dryer for efficient operation. The colour of the peeled dried longan is golden brown for the temperature levels of 50, 60 and 70°C and there is no difference in colour for dried longan for drying at 50 to 70°C.