Edible Oils

Unsaturated Triglycerides

Plant oils are liquid at room temperature due to a high degree of unsaturated triglycerides. Triglycerides are composed of a glycerol base with three fatty acids attached. Unsaturated fatty acids are found in higher concentrations in plant oils compared to animal fats and are recognized for their significant health benefits. Unsaturated fatty acids are constantly at risk of degradation due to environmental oxygen, light, and co-extracted metal ions or metal contact surfaces.

Fatty Acid Oxidation

There are various strategies to slow the rate of fatty acid oxidation and chemical testing is used to monitor oxidation rates. Some common lipid oxidation and quality metrics are peroxide value (PV), anisidine value (AV), and free fatty acid content. Peroxide value (PV) is an early measure of lipid oxidation and indicates the number of unsaturated fatty acids that react with oxygen forming peroxides. Peroxides are unstable and degrade into multiple products that volatilize as off-aromas characteristic of aged, oxidized oils. Next, anisidine value (AV) measures secondary degradation products including aldehydes. The combination of PV and AV data provide insight into the oxidation state of an oil. Free fatty acids are naturally found in unrefined oil and removed during oil refining because they lower oxidative stability. Each of these metrics requires off-line titrations and sample preparation by trained personnel with regularly debated results due to colorimetric indicators with endpoints that vary between technicians. Performing PV, AV, and free fatty acid testing slows operations’ ability to react to lipid oxidation issues during processing.

Near Infrared (NIR) and Raman Spectroscopy

Rapid, non-destructive measurements can provide real time data of your process. Using near infrared (NIR) and Raman spectroscopy can provide real time information about total fat content and lipid oxidation metrics. Oil adulteration is an issue with premium products and can be measured using spectroscopic techniques as well. NIR and Raman spectroscopy can be applied to seed, pressed cakes, and extracts to monitor oil extraction efficiency. Probes can be inserted into production lines to measure flowing oils. Real time data can optimize and automate production parameters for consistent, high quality products and to improve shelf life, consumer acceptance for freshness, and health benefits of edible oils.

Reference:
AOCS Official Methods and Recommended Practices. American Oil Chemists’ Society.