Drying Kinetics and Energy Consumption in Hot-Air and Microwave Drying of Polyscias Fruticosa (L.) Harms Leaves

The experiments were conducted at different air-drying temperatures (45, 50, 55 and 60 °C) for hot air drying and at different microwave power (150, 300, 450 and 600 W) to compare drying kinetics and energy consumption for drying Polyscias fruticosa (L.) leaves. The drying process occurred in the falling period except for hot air drying at 45 °C. The drying behavior of Polyscias fruticosa (L.) leaves could be determined by Midilli or Weibull models. The values of Deff were ranged from 2.557×10−11 to 10.550×10−10 m/s2 for hot air drying and from 3.574×10−10 m/s2 to 10.550×10−10 m/s2 for microwave drying. The activation energies were 54.34 kJ/mol and 8.605 W/g for corresponding to moisture removal by hot air drying and microwave drying. In view of energy consumption and time, microwave drying expressed as a promising drying method for removing moisture from P. fruticosa (L.) leaves. However, it should be considered other criteria such as sensorial values, nutrient retention, etc.