Toward rapid analysis of unsaturated fatty acid oxidation in edible oils via square-wave voltammetry

Authors: THELEN, MATTHEW - University Of Michigan; FLORES, SEBASTIAN - University Of Michigan; KELLEY, JACK - University Of Michigan; SWANK, RIAN - University Of Michigan; Moser, Jill; FHANER, MATTHEW - University Of Michigan

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2025
Publication Date: 6/24/2025
Citation: Thelen, M.M., Flores, S.A., Kelley, J.A., Swank, R.R., Moser, J.K., Fhaner, M.J. 2025. Toward rapid analysis of unsaturated fatty acid oxidation in edible oils via square-wave voltammetry. Journal of the American Oil Chemists' Society. https://doi.org/10.1002/aocs.12973.
DOI: https://doi.org/10.1002/aocs.12973

Interpretive Summary: Deep-fat frying exposes oils to high heat and oxygen, which can rapidly degrade unsaturated fatty acids, resulting in loss of nutrients and the formation of potentially harmful compounds if these reactions are not carefully monitored and controlled. Current methods for monitoring and analysis of oil degradation in industrial deep-fat frying settings are time consuming, and rely on expensive equipment and/or environmentally unfriendly solvents, so there is interest in the development of rapid, environmentally conscious, and reliable methods for monitoring oil degradation during frying. In this study, square-wave voltammetry (SWV), a rapid electrochemical method using an ethanol and ethyl acetate solvent system and a widely available electrode, was evaluated for quantifying linoleic content and its loss over time in canola oil, peanut oil, safflower oil, and soybean oil, heated at frying oil temperature, and comparing to standard gas chromatography (GC) methods. Using a calibration curve and a single-point calibration method resulted in variations in accuracy, however both methods showed a high correlation within each oil type with the GC results for degradation over time, demonstrating SWV's usefuleness as a rapid method for evaluating degradation of heated oils. This technology is of interest to food processors that rely on deep fat frying technology.

Technical Abstract: Square-wave voltammetry (SWV) was investigated as a potential analytical tool for quantitative polyunsaturated fatty acid oxidation in edible oils exposed to high heat. A traditional linear regression calibration curve and a novel single-point calibration method were used to quantitate linoleic acid in oxidized oil samples. These methods were compared a standard method for fatty acid analysis via gas chromatography flame ionization detection (GC-FID). Both GC-FID and SWV methods were able to detect a decrease in linoleic acid concentration for heated oil samples. SWV methods routinely overcalculated the linoleic acid concentration compared to GC-FID analysis. SWV analysis revealed oxidation peaks, which are associated with electroactive compounds, decrease in intensity over time below for peaks below 1.0 V and increase for peaks above this voltage. These findings represent a step forward in electrochemical characterization understanding of heated oils in addition to further advancing electrochemical oil quality screening without the need for specialized electrodes.