Evaluation of Air Drying Characteristics of Sliced Ginger (Zingiber officinale) in a Forced Convective Cabinet Dryer and Thermal Conductivity Measurement

Abstract

A forced convective cabinet dryer is used to study the hot air drying characteristics of sliced ginger placed in a single layer. Ginger is dried from initial moisture content of 87-88% (w.b.) to the final moisture content of 6-7% (w.b.). Experiments are carried out with four different drying air temperatures of 45, 50, 55 and 60°C by keeping the air velocity fixed at 1.3 m/s. The moisture removal rate is found to increase with increase in temperature and drying process occurred at falling rate period for all the temperatures studied. A non-linear regression analysis is conducted to investigate the accuracy of prediction of ten selected thin layer drying models. From the statistical analysis, a best fit curve is obtained which gives better agreement to the experimental drying data. Further, the thermal conductivity of ginger is determined experimentally and a mathematical expression of thermal conductivity as a function of moisture content has been established, which can predict the experimental data within 1.5% accuracy.