Evaluation of drying models of apple (var. McIntosh) dried in a convective dryer

P>Drying behaviour of apple particles was investigated in a laboratory type dryer. The effect of drying air temperature, airflow velocity, initial height of layer, particles shape and size on the dehydration characteristics of apples was investigated. Increase in drying air temperature and increase in the airflow velocity caused a decrease in the drying time and an increase in drying rate. Increase in initial height of layer and increase in the sample thickness caused an increase in the drying time and decrease in drying rate. Drying time of the cubes was shorter and their drying rate was higher than for slices. The experimental dehydration data of apple particles obtained were fitted to the semi-theoretical, empirical and theoretical models. The accuracies of the models were measured using the correlation coefficient (R), mean bias error (MBE), root mean square error (RMSE), reduced chi-square (chi 2), and t-statistic method. All models described the drying characteristics of apple particles satisfactorily (R > 0.9792). The Logarythmic model can be considered as the most appropriate (R > 0.9976, MBE = -10-11-4.5 x 10-6, RMSE = 0.00287-0.01746, chi 2 = 8.5 x 10-6-3.1 x 10-4, t-stat = 7.3 x 10-9-1.2 x 10-3). The effect of drying air temperature, airflow velocity, characteristic dimension of the particle and initial height of layer on the drying models parameters were also determined.