Microwave drying kinetics and quality characteristics of aromatic Pandanus amaryllifolius leaves

The effect of microwave drying technique on drying kinetics of aromatic Pandanus leaves (Pandanus amaryllifolius) was investigated. By increasing the microwave output powers (180-900 W), the drying time decreased from 14 to 2 min. To determine the kinetic parameters, the drying data were fitted to various models based on the moisture ratios versus drying time. Among the models proposed, the semi-empirical Page model gave the best fit for all drying conditions applied. The goodness of fit was determined using the coefficient of determination (R²), reduced chi square (χ²), root mean square error (RMSE). By increasing the microwave output powers, the effective moisture diffusivity values increased from 5.35E-08 to 1.99E-07 m²/min. The activation energy was calculated using an exponential expression based on Arrhenius equation. Further, the effects of the drying conditions on the aromatic compound 2-acetyl-1-pyrroline of the Pandanus leaves were evaluated. Keeping in view the drying time, drying rate and sensory attributes of the leaves, it is proposed to dry the leaves at 540 W in a microwave dryer to obtain the product with good quality.