Analysis of Fatty Acid Methyl Esters in Edible Oils

Significance of the Topic

The profiling of fatty acid methyl esters in edible oils is critical for evaluating nutritional benefits, ensuring product authenticity and detecting adulteration. High oleic acid content in olive oil is linked to cardiovascular health, while the premium value of extra virgin olive oil drives fraudulent dilution along the supply chain.

Objectives and Study Overview

This application note aims to develop and validate a robust gas chromatography–flame ionization detection (GC-FID) method for the quantification of 37 FAME components in various edible oils. The study evaluates method precision, separation efficiency and the ability to identify oil adulteration against International Olive Council guidelines.

Methodology and Instrumentation

Fatty acids were converted to methyl esters by reacting 250 mg of oil sample with 5 mL hexane and 0.25 mL of 2 N methanolic KOH, followed by vigorous mixing and phase separation. The upper hexane layer was injected into a DANI Master GC equipped with a programmable temperature vaporizing injector (PTV), FID detector and Master AS automatic liquid sampler. A cyanopropyl polysiloxane capillary column (50 m×0.25 mm, 0.20 µm film) was used with the following conditions:

• Carrier gas: helium at 1.2 mL/min constant flow
• Oven program: 60 °C hold 6 min, ramp 2 °C/min to 240 °C, hold 2 min
• PTV injector: 40 °C ramped to 260 °C at 999 °C/min, hold 3 min
• Split ratio: 1:80, injection volume 0.8 µL
• FID temperature: 250 °C

Results and Discussion

The method achieved baseline resolution of 37 FAMEs including cis/trans isomers, with retention time and area relative standard deviations below 3% over six injections. Chromatograms of extra virgin and virgin olive oils showed high oleic acid (73.1% and 74.6%) and moderate linoleic acid (7.6% and 8.2%), matching official ranges. Corn oil displayed 53.7% linoleic acid and detectable trans-fatty acids formed during high-temperature deodorization. Adulterated olive oil samples exhibited trans-palmitoleic and trans-linolelaidic esters and a reduced oleic/linoleic ratio (3.93 vs. >7 in genuine EVOO), confirming fraud.

Benefits and Practical Applications

This GC-FID approach enables routine quality control of edible oils, authentication of extra virgin olive oil, verification of geographic origin markers and detection of thermal or fraudulent modifications. The high precision and automation increase laboratory throughput and regulatory compliance.

Future Trends and Possibilities

Advances may include coupling GC with mass spectrometry for enhanced specificity, miniaturized and faster columns to reduce analysis time, integration of chemometric tools for pattern recognition and further automation to support high-throughput screening in industrial environments.

Conclusion

The described DANI Master GC system combined with FID detection and automated sampling delivers a reliable, precise and reproducible method for FAME analysis in edible oils. It effectively differentiates oil types, quantifies key fatty acids and detects adulteration, supporting both health-related and commercial quality assurance.

References

• FDA. Supportive but not conclusive evidence on daily consumption of oleic acid–rich oils (2018).
• International Olive Council COI/T.15/NC No 3/Rev.12. Trade standards for olive oils and olive-pomace oils (June 2018).