Abstract
In this study, the relationship between the electrical properties of frying oil (relative dielectric constant and conductance) and its deterioration indicators (acid value, amounts of polymerized triacylglycerols and chromaticity) were examined, focusing on the changes in electrical properties that accompany deterioration. The samples of frying oil used in this experiment were collected from fried food processing sites (school, hospital and factory feeding centers) and were collected at closing time every day for a maximum of ten days. An LCR meter was used for measurement of the electrical properties of the oil, and the relationships between the deterioration indicators and the electrical properties of samples used for various lengths of time were examined. It was found that more deterioration in the frying oil resulted in a greater relative dielectric constant and conductance. In particular, a clear correlation between the degree of deterioration and the conductance of the frying oil was observed. In addition, the obtained gradient (dG/dT) of conductance temperature dependence of frying oil used in this experiment showed a strong correlation with all deterioration indicators (acid value, amounts of polymerized triacylglycerols and chromaticity). From the above results, it is clear that the degree of deterioration of frying oil can easily be determined based on the conductance temperature dependence.
