Manufacturing update: supercritical extraction

Our new omega-3 oil supplier uses supercritical CO2 extraction – a gentler process that’s better for the environment

Cod liver oil omega 3 gel capsules isolated on white backgroundIgennus is transitioning over to a new omega-3 oil supplier, and several of our products now contain omega-3 oil purified via a cutting edge process called Supercritical CO2 extraction – an alternative to the standard molecular distillation. Supercritical CO2 extraction combines Supercritical Fluid Extraction (SFE) and Supercritical Fluid Chromatography (SFC), delivering the same superior end product in terms of quality and purity, but via methods which are gentler to the oil and kinder to the environment.

The process starts with SFE, which involves using CO2 to gently extract the fatty acids from fish oil and separate them from unwanted fractions such as glycerides, proteins, free fatty acids and cholesterols. Whilst all fish oil must be heated during the purification process (even those described as cold extraction will have been subjected to some level of heat), molecular distillation uses additional heat and chemicals to help remove these impurities. This does not affect the quality of the final product, nor the high level of purity, but CO2 extraction avoids this altogether, which is kinder to the oil and the environment.

Using CO2 extraction also helps ensure the oil doesn’t come into contact with oxygen, further protecting the omega-3 fatty acids against oxidation and from those organisms that would otherwise thrive in an oxygen environment.  In addition, heavy metals and other impurities are insoluble in CO2, which allows for an extremely high level of purity to be achieved without the use of chemicals.

Removing the impurities deodorises and purifies the oil, and once this process is complete, the oil filters through to begin the Supercritical Fluid Extraction process, passing through a chromatographic column packed with a highly selective separation material. While passing through this column, the fatty acids get separated according to their size and degree of molecular structure. First saturated fats are removed, followed by monounsaturated fats and then each individual (EPA, DPA & DHA) polyunsaturated fat leaves the column at separate intervals.  Finally the CO2 is released, allowing for an exceptionally high purity and stability of EPA and DHA fatty acids in the final omega-3 concentrate.


Oxidation is the chemical decomposition of fats, oils and other lipids by oxygen in the air.  All oils are susceptible to oxidation, so protecting oil from deterioration and subsequent production of oxidised end products is essential for maintaining long-term stability. In addition to using CO2 extraction methods, we also encapsulate our oil and, in the case of our therapeutic products, we blister pack individual capsules much like pharmaceutical packaging. The addition of an antioxidant such as vitamin E to our oils also helps to ensure long-term stability. It is through this combination of processes that we can provide an end product that meets the highest standards in terms of freshness and stability.  In addition, our oils are routinely tested before and after packaging so that our customers can be confident in our guarantee that the oil is the highest possible quality at all stages of the manufacturing process, as well as for its full packaged life.

Measuring oxidation: looking at both peroxide value and TOTOX 

Measuring oxidation involves testing for the primary and secondary breakdown products.  The most common test, the peroxide value (PV) is an indication of levels of primary oxidation end products and the lower the PV the better the quality of the oil.  However, the PV decreases as secondary end products are produced and therefore analysis of secondary end products is used to determine the Anisidine Value (p-AV), which is used together with the PV to determine the TOTOX value (determined by the formula AV + 2PV) and indicates the oil’s overall oxidation state.  The PV should not be greater than 5, the AV no greater than 20 and the TOTOX no greater than 26.

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Dr Nina Bailey

About Dr Nina Bailey

Nina is a leading expert in marine fatty acids and their role in health and disease. Nina holds a master’s degree in Clinical Nutrition and received her doctorate from Cambridge University. Nina’s main area of interest is the role of essential fatty acids in inflammatory disorders. She is a published scientist and regularly features in national health publications and has featured as a nutrition expert on several leading and regional radio stations including SKY.FM, various BBC stations and London’s Biggest Conversation. Nina regularly holds training workshops and webinars both with the public and health practitioners.