Determination of microwave and convective drying characteristics of coriander leaves

Abstract

Coriander leaves, which weighs 50 ±0.07 g with moisture of 7.531 ± 0.411 [kg(moisture) kg-1 (dry matter)], were dried using three drying methods, microwave, convective and natural drying. Drying continued until leaves moisture was reduced to 0.102 ± 0.0002 [kg(moisture) kg-1 (dry matter)]. Drying treatments in microwave drying powers were 100, 500 and 1000 W and drying periods lasted 9 – 76 min for microwave drying. While natural drying was lasted for 6 days, convective drying (50°C) was continued for 169 minutes. In this study, measured values of moisture were compared with predicted values obtained from several thin-layer equations. The best model for both 1000 W and 100 W microwave drying was Alibas’s model. Whereas the best model was determined as Verma’s model at 500 W, the most appropriate model was modified Henderson Pabis’s model in convective drying at 50°C. The optimum drying period, color and chlorophyll content were obtained by using the microwave drying at 500 W.