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민용규,정헌상 충북대학교 농업과학기술연구소 1991 農業科學硏究 Vol.9 No.2
In order to predict the quality of edible oils with electric properties the dielectric properties of the fresh and the thermally oxidized soybean and corn oil were determined at room temperature in the frequency from 0.2 to 100kHz, and also physical and chemical properties of these oils were determined by AOAC methods and the correlationship among these properties was investigated. Thermal oxidation was carried out at 180℃ for 12 hrs. The dielectric constant of edible oils showed the characteristic of Debye's dispersion with frequency and remarkable decrease around 1kHz. Dielectic loss tangent showed the peek around 4kHz frequency. These phenomena could be thought as the result from the frequency properties of dipole orientational polarization. Due to the increase of polar materials, free fatty acid value, peroxide value, density, dielectric constant, and dielectric loss tangent increased in proportion to the thermal oxidation time. Accordingly, the index of rancidity of edible oils could be predicted by measurement of the dielectnc properties. Key Words : Soybean oil, Corn oil, Dielectric constant, Thermal oxidation, Dielectric loss tangent.