Effective Moisture Diffusivity, Activation Energy and Dielectric Model for Palm Fruit Using a Microwave Heating

A microwave heating process for palm fruit can quickly remove the moisture content and destroy any free fatty acids (FFA) in palm fruit. In this paper, the key parameters for palm fruit to design an effective microwave heating system, effective moisture diffusivity, activation energy and dielectric model are reported. These parameters can predict the temperature distribution and moisture ratio in var. Tenera palm fruit when using a 2.45 GHz microwave, heating at four different power levels (160, 320, 480, 800 W). By assuming that each palm layer is homogeneous, a model composed of physical layers (mesocarp, shell and kernel) was developed. The effective moisture diffusivity of the palm fruit is determined by Fick’s second law for mass transport mechanism. The calculated value of the effective moisture diffusivity of the palm fruit increases with the temperature since the water molecules in the palm fruit diffuses quickly at high temperature. In addition, the activation energy of palm fruit ranges from 31.06 to 48.91 kJ(mol)-1 with the different microwave powers, which were obtained by applying the linear regression technique to the Arrhenius equation model. Finally, the comparisons between the computed and the actual experiment for the moisture ratio with the different microwave powers were computed from the effective moisture diffusivity in the palm fruit. The results obtained from both data sets highly correlate.