Drying kinetics of single layer Thompson seedless grapes under heated ambient air conditions

For determination of drying kinetics of Thompson seedless grapes a suitable experimental unit for online measurement was designed and fabricated. The drying characteristics of oil emulsion pretreated grapes were measured for all ranges of temperature (50 to 80°C) and velocity (0.25 to 1.00 m/s) of the ambient air which may be used for drying purposes. Out of the three models con sideTed (Page's, Single term and Two term exponential) Page's model was found to be the most suitable for describing the drying behaviour of the grapes. The dependence of drying constant k of Page's model on process variables (Temperature and Velocity of air) was analysed using Arrhenius and power law model. It was found that the Arrhenius model gives better values of k than the power law model. It is also found that the dependence of another drying constant N of the Page's model on the process variables can not be described in terms of Arrhenius or power law model.