Microwave Drying Characteristics and Kinetics of Lotus (Nelumbo nucifera Gaertn.) Seeds

Lotus (Nelumbo nucifera Gaertn.) seeds were dried in a laboratory quality microwave oven to determine the effects of microwave output and mass load on drying time and drying rate. By increasing the microwave output power (231-539 W) and mass load (100-200 g), the drying time decreased from 36 to 13 min and increased from 18 to 30 min, respectively. The drying process can be divided into three stages: the heating period, constant rate period, and falling rate phase. A kinetics model which could describe the relationship of moisture ratio and drying time was established based on experimental data. The results show the drying procedure of lotus seeds could accurately be described by the Page model. The predicted values of the model were nearly consistent with the observed values. The moisture content and drying rate during the drying procedure matched the predicted results estimated by the Page model.