Thin-layer drying of litchi ( Litchi chinensis Sonn .)

Abstract

This article presents the thin-layer drying of peeled litchi, which was conducted under controlled conditions of temperature and relative humidity. It was observed that the drying temperature has some influence on the drying rates of peeled litchi, so that the higher the temperature the less the drying time. Eight different thin-layer models were fitted to the experimental data of peeled litchi. The drying parameters of peeled litchi were found to be a function of drying air temperature and relative humidity. The Page model was revealed to be the best and it was followed by the logarithmic models. The agreement between the predicted and experimental values for the Page model is excellent, so that this can be used to provide design data and for simulation and optimisation of the dryer for efficient operation. The colour of the dried litchi was light golden brown and it remained almost unchanged for drying at 50 °C, 60 °C and 70 °C. Therefore, the quality change of the dried litchi in terms of colour change was not significant for drying in the temperature range of 50–70 °C.