Edible oils are essential for our diet. Various parameters are used to assess oil quality including the determination of iodine value, free fatty acids (FFA), refractive index, and fatty acid composition. Fatty acid composition analysis provides a detailed view regarding the concentration of different fatty acids present in the oil. The content of essential linoleic acid (C18:2) and alpha-linolenic acid (C18:3) are especially interesting for edible oil producers.

Traditional analysis techniques like titration or gas chromatography can be time consuming and often require the use of hazardous solvents which can pose health risks and increase analysis costs. In contrast to these standard methods, each of the mentioned edible oil quality parameters can be analyzed simultaneously, without sample preparation, and in a few seconds via near-infrared spectroscopy (NIRS) with the OMNIS NIRS Analyzer.

The obtained NIR spectra (Figure 2) were used to create prediction models to quantify all eight oil quality parameters: iodine value (IV), FFA, refractive index, palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2), and alpha-linolenic acid (C18:3). The quality of the prediction models was evaluated using correlation diagrams which display a high correlation (R² > 0.94) between the NIR prediction and the standard reference methods for all parameters. Out of the total, 25% of the samples were selected as the validation set and the other 75% as a calibration set. The respective figures of merit (FOM) display the expected precision and confirm the feasibility during routine analysis (Figures 3–10).