Convective dehydration kinetics of osmotically pretreated pomegranate arils

The freezing of the whole pomegranate at −18 °C was carried out prior to convective dehydration to increase the permeability of the outer layer of the arils. The arils were osmotically pretreated in 50°B of sucrose solution at 40 °C for 100 min with fruit to solution ratio of 1:4 (w/w). The osmotically dehydrated arils were further dehydrated convectively at different drying air temperatures of 50, 60 and 70 °C up to final moisture content of 9 ± 1% (w.b). Among the models investigated, the Middilli model fitted the experimental data for convective drying of natural and osmosed pomegranate arils. During convective dehydration, the average effective moisture diffusivity of natural samples and osmosed samples at drying air temperatures ranging from 50 to 70 °C varied between 2.60 × 10−10 to 4.89 × 10−10 m2 s−1, between 3.37 × 10−10 to 5.04 × 10−10 m2 s−1, respectively. The activation energy was 66.12 kJ mol−1 for natural samples and 42.06 kJ mol−1 for osmosed samples, respectively.