Development and Evaluation of an Impedance Spectroscopy Sensor to Assess Cooking Oil Quality

Abstract

When the cooking oil is used repeatedly, severalunwanted substances are generated, which may cause healthproblems. This study was conducted to determine the possibilityof using the impedance spectroscopy to differentiate amongvarying cooking oil quality at various intervals of heating timeat constant temperature. The frequency has started from 100Hz to 100kHz. Fresh, 10-hour, 20-hour, 30-hour, and 40-hourheated cooking oil was prepared by using lab oven attemperature of 180oC. In this study, a sensing probe wasdesigned to measure the electrical properties of the oil samples.The oil samples were analyzed using a viscometer to measurethe viscosity of the oil, a sensor to measure total polarcompound (TPC), and an impedance probe connected to a LCRmeter to measure the electrical properties of the oil. Themeasurements were analyzed and correlated with oil qualityparameters obtained from a viscometer and a sensor of TPC.The discrimination between different heated hours of oilsamples was examined and the results were compared to theirphysico-chemical properties such as viscosity and total polarcompounds. The effect of heating of frying oils were successfullyevaluated and discriminated using the impedance spectroscopy.Significant correlations (r -0.98472) were found betweenchanges in total polar compound properties of oil and theimpedance values.