Monitoring Lipid Oxidation in Different Lipid Matrices by Dielectric Spectroscopy Using an Open-Ended Coaxial Probe

Lipids undergo oxidative degradation during storage, leading to quality deterioration and potential health risks; therefore, rapid and reliable monitoring methods are needed. This study evaluated dielectric measurements as an alternative approach to determine the oxidative status of different lipid systems (bulk oil, emulsion, and fatty acid methyl esters, FAMEs) during auto-oxidation. Samples were analyzed simultaneously by conventional chemical methods (peroxide value, p-anisidine value, and induction time) and microwave dielectric measurements in the 2-20 GHz frequency range using a coaxial probe. Strong correlations were observed between dielectric parameters and peroxide values as well as induction time in all lipid systems. Good correlations were also found between dielectric data and p-anisidine values in bulk oil and FAMEs, whereas correlations were moderate in emulsions. The results demonstrate that dielectric measurements show strong potential as a rapid, non-destructive, and environmentally friendly approach for assessing lipid oxidation.