Complex permittivity of fully ripe palm fruit from 1–30 MHz

Abstract

This paper presents complex permittivity of each layer of fully ripe palm fruit var. Tenera at frequency from 1 to 30 MHz. The complex permittivity data of palm fruit which can be described in terms of dielectric constant and loss factor is very crucial to design a radio frequency (RF) system for heating palm fruit. From our measurement, the characteristics of the capacitance, dielectric constant and loss factor of all palm fruit layers decrease significantly with frequency. The loss tangent of the kernel and mesocarp layers is higher than the shell layer; meaning that both kernel and mesocarp layers can absorb radio energy and convert to heat more efficient than the shell layer. Applying the radio wave either at 13.56 or 27.12 MHz, the penetration depths of mesocarp and kernel layers are computed and found to be several times thicker than the their thickness values. This confirms that an efficient RF heating mechanism in mesocarp and kernel layers can be obtained.