Analysis of Edible Oils Using FT-NIR Spectroscopy

Fats and oils are recognized as important nutrients in the human diet, being consumed in a variety of forms. Rapid quality control of edible oils can be achieved by Bruker Optics dedicated FT-NIR spectrometers. The analysis is quick, economical and safe to use, even for untrained staff.

Parameters to Assess Edible Oil Quality

The different indicator parameters used to assess the quality of edible fats and oils are:

• Iodine value (IV).
• Free fatty acids (FFA).
• Trans Fatty Acids (TFA).
• Anisidine value (AV).
• Fatty acid profile (C16:0, C18:0, C18:1, C18:2, C18:3, etc.).
• Various other parameters.

Among those parameters, the TFA content is a mandatory legal labelling requirement under the new guidelines of the U.S. Food & Drug Administration.

Conventional Techniques for Edible Oil Analysis

Conventional analyses are normally done using standardized chemical and physical methods sanctioned by the American Oil Chemist Society (AOCS) and/or the association of Official Analytical Chemists (AOAC). However, these techniques are designed for the analysis of only one specific parameter and tend to be time consuming, costly and often performed with hazardous solvents and reagents.

With conventional gas chromatography (GC), the profile of Iodine value (IV), trans and fatty acid can be studied simultaneously, but the analysis takes more than half an hour, not including the time to prepare the sample. Edible oil producers and food processors are therefore seeking alternative fast and non-destructive ways to analyze fats and oils for process and quality control purposes.

Advantages of NIR for the Edible Oil Analysis

The advantages of NIR for edible oil analysis are:

• Near infrared (NIR) spectroscopy is rapid (the analysis time is roughly less than 1 minute) and capable of analyzing multi-components simultaneously in a single measurement.
• It is non-destructive.
• There is  no need for specific sample preparation, and it does not require the use of any solvents or reagents.
• It performs real-time measurements with associated time and cost savings.
• The technique is well recognized and AOCS method Cd1e-01 uses FT-NIR to measure Iodine Value (IV).
• FT-NIR spectroscopy has the potential to substitute a wide range of classical analysis methods in the edible oil industry. Bruker Optics offers ready-to-use calibrations for edible fats and oils to enable a quick and efficient start.

Further Applications with FT-NIR Spectroscopy

The other applications of FT-NIR Spectroscopy are:

• Other than analyzing edible oils and fats, FT-NIR has a huge potential in analyzing oil seeds and residues for oil and moisture content to optimize pressing processes.

• Rape seed breeders can obtain valuable additional information like the content of fatty acids such as Erucic acid and Glucosinolate.

• Near Infrared spectroscopy is a fast and economic method to assess the quality of deep-frying oil with regards to its key parameters: Total Polar Compounds (TPC) and Polymerized Triacylglycerols (TAG).

Figure 1. FT-NIR absorption spectra of oil samples in the range of 4,500 to 10,000 cm^-1.

Figure 2. Validation results of the Iodine Value (IV) calibration, based on a variety of different oils.

Figure 3. Detailed view of the spectral region used for the IV calibration.

Figure 4. Validation results of the FFA calibration, based on olive oil, palm oil and various other oil types.

Figure 5. Validation results of the TFA calibration, based on a variety of different edible oils.

Figure 6. Validation results in a low range from 0 to 2.5% TFA.

Figure 7. Validation results for Oleic Acid, based on various edible oils like palm, soya and sunflower oil.

This information has been sourced, reviewed and adapted from materials provided by Bruker Optics.

For more information on this source, please visit Bruker Optics.