Determination of olive oil purity based on triacylglycerols profiling by UHPLC-CAD and principal component analysis

Significance of the Topic

Olive oil adulteration threatens consumer safety and product authenticity. Conventional purity assays using fatty acid and sterol profiling are resource-intensive, often outsourced, and generate chemical waste. A streamlined in-house method can enhance quality control and reduce costs.

Objectives and Overview of the Study

The study aimed to establish a rapid approach for detecting olive oil adulteration by profiling triacylglycerols (TAGs) via ultra-high-performance liquid chromatography with charged aerosol detection (UHPLC-CAD), followed by principal component analysis (PCA). It evaluated pure extra virgin olive oils, five common adulterant oils, and their binary blends.

Methodology and Instrumentation

Sample Preparation:

• Oil diluted to 1 % (v/v) in methanol/chloroform (50:50, v/v).
• Vortexed and transferred to amber autosampler vials.

Instrumentation:

• UHPLC System: Thermo Scientific Vanquish Flex with quaternary pump, split sampler, column compartment.
• Detector: Vanquish Charged Aerosol Detector (CAD) at 50 °C, 10 Hz collection.
• Column: Accucore C18 (2.6 μm, 100 × 2.1 mm) at 50 °C.
• Mobile Phase: Acetonitrile (A) and isopropanol (B) gradient from 10 % to 90 % B over 35 min at 0.5 mL/min.
• Data Analysis: Peak area percentages computed in Chromeleon 7.2.6; PCA executed in OriginPro 2016.

Main Results and Discussion

• PCA of eleven TAGs separated six oil types into distinct clusters with over 81 % variance explained by the first two components.
• Adulteration detection limits ranged from approximately 5–10 % depending on the adulterant.
• Optimized three‐TAG PCA models improved quantification of specific blends (e.g., LLL, OLL, OOO for grapeseed oil).
• A blind test accurately predicted a 45 % olive oil content in an unknown blend with grapeseed oil.

Benefits and Practical Applications

• Rapid adulteration screening without extensive sample prep.
• Single TAG profiling replaces separate fatty acid and sterol tests.
• Reduced solvent use enhances environmental sustainability.
• Cost-effective in-house implementation avoids external laboratory fees.

Future Trends and Applications

• Expansion to other edible oils and complex blends.
• Integration with advanced chemometric and machine learning algorithms.
• Potential coupling with high-resolution MS for deeper compositional insights.
• Miniaturized or on-line UHPLC-CAD systems for real-time quality control.

Conclusion

UHPLC-CAD combined with PCA of TAG profiles provides a robust, efficient, and eco-friendly method for olive oil purity verification. The approach enables detection of low-level adulteration, streamlines laboratory workflows, and supports quality assurance in the olive oil industry.

Reference

1. Arlorio M. et al. Food Addit Contam A. 2010;27(1):11–18.
2. International Olive Council. Determination of TAG ECN 42. 2001.
3. Green HS et al. Food Control. 2020;107:106773.
4. Indelicato S. et al. J Chromatogr A. 2017;1515:1–16.
5. Lucci P. et al. J Food Comp Anal. 2018;66:230–236.
6. Lísa M. et al. J Chromatogr A. 2007;1176(1-2):135–142.
7. De la Mata-Espinosa P. et al. Food Anal Methods. 2011;4(4):574–581.
8. De la Mata-Espinosa P. et al. Talanta. 2011;85(1):177–182.
9. Abdi H., Williams LJ. WIREs Comput Stat. 2010;2(4):433–459.
10. Yang Y. et al. J Agric Food Chem. 2013;61:3693–3702.