Dielectric constant and induced dipole moment of edible oils subjected to conventional heating

Abstract

The frequency dependence of dielectric constant, dielectric loss factor and conductivity are studied for five edible oils in the frequency range 100 kHz to 13 MHz at different temperatures using frequency domain spectroscopy. The dielectric constant is found similar for all the samples and in agreement with the previous reports. The dielectric loss is low (<0.01) except for the virgin olive oil with value of 0.05. Dielectric loss peak frequency is at 4 MHz for corn oil and around 5.2 MHz for the others. At this frequency conductivity is of the order of 10-7-10-9 S/cm, and decreases with temperature following the behavior of the dielectric losses. Refractive index, molar and orientation polarization are calculated for all types of oils using novel theory proposed by N. M. Putintsev and D. N. Putintsev [1]. Data show that the orientation polarization contributes to the observed dielectric constant at low temperatures and frequencies. This indicates that the edible oils are not pure nonpolar dielectrics. Induced dipole moments of oils are calculated for 400 kHz and 10 MHz at 300 K and 318 K. The results are discussed and correlated as a function of temperature and frequency to establish their relationship.

Keywords

• dielectric constant, edible oils, molar polarization, specific refraction, dipole moment