The Dielectric Property of Soybean Oil in Deep‐Fat Frying and the Effect of Frequency

ABSTRACT: : Suitability of the dielectric constant for real time and continuous evaluation of frying oil was investigated. Measurements of the dielectric capacitance, in the frequency range 1 kHz to 100 kHz, were made on soybean oil heated at several temperatures (180, 200, 220, and 240 °C) for a few d. Frequency dependence was also measured between 50 Hz and 30 MHz. The dielectric constant of the soybean oil increased with increase in the heating time, and was well correlated with acid value, density, and relative viscosity. Our equipment for measuring capacitance would be available for real time and continuous evaluation of frying oil quality in the food industry.