Fast Ingredient Analysis of Edible Oils Using a Portable Raman Spectrometer

Significance of the Topic

The analysis of edible oils is critical for ensuring nutritional quality and monitoring lipid oxidation processes in the food industry. Traditional methods such as gas chromatography–mass spectrometry require extensive sample preparation and laboratory settings. Portable Raman spectroscopy offers rapid, nondestructive testing at-line, enabling real-time insights into oil composition and quality.

Objectives and Study Overview

This application note demonstrates the use of a handheld Raman spectrometer to quantify key fatty acid constituents—oleic acid, linoleic acid, mono- and polyunsaturated and saturated fatty acids—in five types of edible oils. The study aims to develop and validate chemometric calibration models for rapid component determination in at-line environments.

Methodology and Instrumentation

A total of 150 oil samples (30 each of olive, camellia, peanut, sunflower, and canola oil) were analyzed using an i-Raman portable spectrometer with 785 nm excitation. Spectra were collected over 175–2600 cm-1 with a 9 s integration time, using a 10 mm pathlength cuvette holder. Reference concentrations were obtained by GC-MS. Spectral preprocessing (baseline correction and Savitzky-Golay smoothing) and Partial Least Squares regression were performed in BWIQ chemometrics software to build quantitative models.

Results and Discussion

The PLS models achieved strong performance for oleic acid (R=0.95, RMSEP=0.24), linoleic acid (R=0.97, RMSEP=0.17), mono-unsaturated fatty acids (R=0.96, RMSEP=0.23), polyunsaturated fatty acids (R=0.98, RMSEP=0.15) and saturated fatty acids (initial R=0.84, RMSEP=0.15). Outlier detection in BWIQ enabled removal of anomalous samples, improving the saturated-fatty acid model. Predicted concentrations closely matched GC-MS reference values, demonstrating the reliability of the portable system for oil composition analysis.

Benefits and Practical Applications

• Rapid, nondestructive analysis without sample preparation
• Field-portable instrumentation suitable for at-line quality control
• High spectral resolution comparable to benchtop systems
• Versatile measurement of oils in disposable cuvettes

Future Trends and Potential Applications

Advances may include ingredient-specific calibration models for enhanced accuracy, broader deployment in food processing lines, integration with cloud-based analytics platforms, and expansion to other lipid-based products. Continued miniaturization and improved chemometric algorithms will further empower rapid, on-site oil quality monitoring.

Conclusion

This study confirms that portable Raman spectroscopy combined with multivariate analysis provides a fast, accurate, and noninvasive method for quantifying fatty acids in edible oils. The approach is well suited for routine at-line quality control in the food industry.

Reference

• Bruno Bernuy Marc Meuren et al Determination by Fourier Transform Raman Spectroscopy of Conjugated Linoleic Acid in I2-Photoisomerized Soybean Oil Journal of Agricultural and Food Chemistry 2009 57(15):6524–6527 DOI 10.1021/jf9003237
• Barbara Muik Bernhard Lendl Antonio Molina-Diaz Direct monitoring of lipid oxidation in edible oils by Fourier transform Raman spectroscopy Chemistry and Physics of Lipids 2005 DOI 10.1016/j.chemphyslip.2005.01.003
• B&W Tek BWIQ Raman Quantitative Software http://www.bwtek.com/products/bwiq
• B&W Tek Shanghai Central South University ChemSolve Ltd AppNote No.20120710C