Investigation of Black Mulberry Drying Kinetics and Energy Consumption under Microwave Oven

Black mulberry is a soft fruit that is quite sensitive to the mechanical damage during the harvesting and therefore susceptible to the microbial contamination and cannot be properly stored due to the short harvest season and low shelf life. Drying methods are used to increase it’s shelf life. Drying is the oldest method of food preservation. Drying preserves foods by removing enough moisture from the food and reduces the microbiological activities and minimizes the physical and chemical changes during storage. In this research, drying kinetics, moisture diffusivity, appropriate mathematical modeling and activation energy of black mulberry were studied under microwave oven.
Dring of black mulberry using microwave oven was performed at four power levels (200, 300, 400 and 500 W) and the results were compared. Samples weighing was performed every 30 seconds by a digital scale (GF600-Japan). For mathematical modeling, nine empirical models were fitted on the experimental data and then according to the most value of R2, the lowest value of c2and RMSE, the best mathematical model was selected with the highest accuracy.
The result of regression analysis showed that Midilli model has the best fitting with the data. Moreover, the highest value of moisture diffusivity was obtained at 3.28×10-5 m2/s at the power of 500 W and the lowest value of moisture diffusivity was obtained at 9.58×10-6 m2/s at the power of 200 W.
The results of this study indicated that microwave drying method might be suitable for the reduction of moisture content in fruits such blackberry.