Drying Kinetic Studies on Single Layer Thompson Seedless Grapes Under Controlled Heated AIr Conditions

A batch type experimental dryer with online weighing mechanism was developed for studying thin layer drying kinetics of Thompson Seedless grapes under the entire range of controlled drying air conditions expected to be used in commercial drying of grapes. Thin layer drying rates of grape berries pretreated with commercial dipping oil were experimentally determined at four levels of drying air temperature (50, 60, 70 and 80C), four levels of airflow velocity (0.25, 0.50, 0.75 and 1.00 m/s) and three levels of air relative humidity (13, 18 and 23%). the Page's equation drying rate constants k and N were obtained for each experimental run conditions. Correlations of drying rate constant k with drying air condition variables T, V and H was determined in terms of Arrhenius type model and power model. the obtained data fitted well in to the Arrhenius type model compared to power model.