Fish Oil Omega-3 Concentration And Refinement Process

Marine fish oil lipid is a popular dietary supplement that is rich in Omega-3 long-train polyunsaturated components. These essential fatty acids are important for maintaining good health and have been linked to a wide range of health benefits, including reducing inflammation, improving heart health, and supporting brain function.

The concentration and refinement process of fish oil ester has been applied to many fish species since 2000, and they are fundamental technologies to ensure high content and purity of Omega-3 ingredient production.

This article will introduce highly efficient process technologies in the practice and equipment that have been used for Omega-3 concentration and refinement.

Step 1: Harvesting and Extraction

The first step in the process is to harvest the Omega-3-rich fish and extract the oil from their tissues. Several species of fish, depending on the living regions can be used to produce Omega-3 fractions like docosahexaenoic acid (DHA), docosapentaenoic acid (DPA), and eicosapentaenoic acid (EPA). The most commonly used species for fish oil extraction are anchovy, sardine, mackerel, and salmon.

The raw material is divided into three major parts: solids, oil, and water. They can be extracted through wet pressing, the use of solvents, and more recently through enzymatic processes which is the use of supercritical fluids and the creation of chemical or biological silages.

Wet Pressing

Wet pressing is the most widely used method for producing fish oil on an industrial scale, and it essentially involves four steps: heating the fish, pressing, decanting, and centrifuging. Due to breakdown processes including hydrolysis and oxidation, severe temperature and pressure conditions utilized for protein coagulation and subsequent oil release may partially alter the omega-3 (PUFA) present.

Hollow-Spiral-Cooker, Screw conveyer, Double Screw Press

Solvent Extraction

Another common practice is solvent extraction, which is typically used for analytical purposes but not for industrial production due to the drawbacks of employing compounds that are restricted in the food sector. This method is based on the solubility of lipids in organic solvents and their insolubility in water, allowing them to be separated from water along with their soluble components such as proteins, carbohydrates, and minerals. The disadvantages of this method include the need for a sufficiently dry sample that must be destroyed, the length of time required, and the amount of residual solvent produced.

Supercritical Fluid Extraction

Supercritical fluid extraction is an innovative extraction process that uses solvents and has gained popularity in recent years due to benefits such as the use of a moderate temperature, and an oxygen-free environment. In comparison to ordinary solvents, supercritical fluids have lower viscosities and higher diffusivities, which improve mass transfer and shorten extraction times overall.

Extraction by Fish Silage

Fish silage is a semi-liquid product formed from whole fish or fish parts that have had the protein hydrolyzed by the addition of acids (chemical silage), enzymes (silage or enzymatic extraction), or lactic acid bacteria (biological silage). This procedure has been demonstrated to be a good replacement for conventional techniques because it can be easier to use and less expensive in terms of investment and energy expenditures.

The physicochemical and microbiological changes brought about by this technology’s lack of solvents and high temperatures can both improve extraction performance and stop undesired processes, such as fat oxidation. Additionally, functional components including protein hydrolysate, collagen, and essential fatty acids can also be restored.

Impurities in crude oil vary depending on the extraction method used and require a refining and concentration process to achieve high-quality features suitable for human consumption. The following refining and concentration processes are properly optimized to minimize oil loss and enhance the availability of useful ingredients. Various contaminants must be eliminated while keeping the most desirable compounds, such as omega-3 and other PUFAs to attain great features.

Step 2: Filtration

Once the oil is extracted, it is filtered to remove any impurities and unwanted substances, such as heavy metals, PCBs, and dioxins.

Fish oil is separated efficiently by the process flow of horizontal spiral tricanter, press liquid heater, disk centrifuge, and heater with mixer. The liquid phase product becomes feed-grade crude fish oil. The water phase is 100% recycled to the concentrating system.

Fish Liquid Treatment System, with filtration with disk centrifuge

According to the oil content of different raw materials, the process and parameters will be adjusted to ensure the separation of oil from the water almost completely.

Step 3: Refining Processes

The polyunsaturated fatty acids in deep-sea fish oil, including EPA/DHA, are thermally and chemically unstable substances and are highly susceptible to oxidation during processing, making the content of EPA in the finished fish oil significantly reduced, making it difficult to meet health dietary needs and unable to achieve good medical value. The polyunsaturated fatty acids in fish oil need to be further refined, concentrated and purified.

Refining deep-sea crude fish oil typically involves a series of processes designed to remove impurities and improve the purity and quality of the oil. Here are some of the steps involved in refining and obtaining triglyceride(TG) type fish oil.

  • Degumming

Acid and water degumming are standard industrial degumming procedures. The hydratable phospholipids compounds in fish oils are removed during the water degumming process by treating them with water or vapor, typically at high temperatures.

Centrifugation is used to separate the resultant hydrated phospholipids from the oil when they become immiscible there. The addition of phosphoric or citric acids increases phospholipid hydration during acid degumming.

  • Neutralization

Most contaminants in unpurified fish oil can be removed using the neutralization method. Caustic soda is used during the neutralization process to get rid of free fatty acids (FFA) from unpurified oil. The crude and neutralized fish oil will be distinguished by the following measurements, both chemical and physical: the acidity content (% oleic acid), peroxide, acid, saponification values, and neutralization yield. The neutralization process involves the removal of acidic contaminants to prevent oil modifications.

Bleaching is one of the most significant phases in the fish oil refinement process which results in acceptable quality products. Fish oils are bleached to enhance their color quality while preserving their polyunsaturated fatty acid content.

In the bleaching process, zeolites & bleaching earth are introduced to fish oil to reduce the content of heavy metals, colors (such as carotenes and chlorophylls), and phosphorus that is left out after degumming. Activated white clay adsorption reduces the peroxide value. This enhances the oil’s aroma and appearance.

The final phase in the refinement process for fish oil is deodorization, which aims to get rid of unpleasant smells. The most used method of deodorization is steam distillation. The remaining free fatty acids (FFA) and the majority of the lipid oxidation products, aldehydes, and ketones are eliminated.

The pre-processed fish oil semi-finished products are heated to the appropriate temperature in the deodorizing kettle and then fed with superheated steam at the appropriate pressure and held for the appropriate time to allow the steam to remove the fishy components from the fish oil.

combined packing type deodorization tower
deodorization system with SS316L packing, fatty acids trap, steam injection units to solve the odor problem completely.

The oil is then subjected to a process called winterization, which involves partially crystallizing the oil through controlled cooling to a certain low temperature usually around 0 to -6°C, causing the fats and impurities to solidify and separate from the oil.

Its main goal is to distinguish saturated from unsaturated fatty acids and separate them. This separation is made possible by differences in the melting temperatures of the fatty acids, which are primarily influenced by the chain length and degree of unsaturation. This causes mostly stearin or other solids to solidify and separate from the oil, which can then be removed through filtration.

As a result, while PUFAs stay in liquid form in the oil, saturated and other mono-unsaturated fatty acids crystallize to be separated. Sometimes organic solvents are used in the winterization process to improve the rate of mass transfer and fraction crystallization of saturated fatty acids from oil dissolved in a suitable solvent.

The winterization process can be repeated several times to increase the purity of the oil. The outlet oil is typically clearer and less viscous, making it easier to handle and more appealing to consumers.

In addition to improving the purity of the oil, winterization can also help to increase the shelf life of the product by removing unstable fats that can oxidize and become rancid over time.

winterization process tank system with complete PLC control system
  • Optional steps:

Depending on the desired final product, additional steps may be taken, such as adding antioxidants or further refining the oil to improve its purity, stability, and overall quality.

Step 4: Concentration

When you need to get higher Omega-3 content, it is crucial to concentrate the fish oil ester with advanced processes including esterification, chromatographic fractionation, enzymatic concentration, urea absorption, membrane filtration, and molecular short-path distillation. According to the data gathered, combining several established and cutting-edge technologies is becoming more prominent to increase yields and purity.

Here are the general steps for concentrating fish oil ester:

  • Esterification Process:

Esterification is a process that involves combining sulphuric acid or alkali as a catalyst and mixing it with anhydrous ethanol, water, and fatty acid to form an ester. This step is done before the oil is purified and concentrated.

The mixture is then heated to a specific temperature, typically around 60-80°C, for several hours to allow the complete reaction to occur. The reaction creates esters, which are more stable than the Omega-3 fatty acids found in fish oil.

After the reaction is complete, the mixture is neutralized with a base such as sodium bicarbonate to remove any remaining acid. After the esterification is complete, the excess ethanol is distilled out and recovered through a condenser.

The esterified fish oil will be further separated from the alcohol and any remaining impurities using various separation methods such as scrape film evaporation, short-path molecular distillation, high-performance liquid chromatography, or centrifugation.

  • Enzymatic Methods

Enzymatic methods for concentration are based on the selectivity of particular lipases for specific fatty acids or spots in the triacylglycerol molecules, catalyzing processes such as hydrolysis, alcoholysis, or transesterification. These techniques must be used before additional phases, such as molecular distillation or membrane filtration, to obtain omega-3 fatty acid concentrations.

Short-path distillation is a highly efficient thermal heating process used to remove free fatty acids and concentrate liquids of thermal sensitivity and with high boiling points, such as fish oil with Omega-3 PUFAs. The vacuum pump group is specially designed to create a low-pressure environment in the system maximum to 0.1Pa, which reduces the boiling points and aids in purification process of deodorization, removal of free fatty acids, glycerol and solvent residues.

The glyceride content of the obtained product is less than 0.5%, glycerol content is less than 0.5%, solvent ethanol content is less than 50ppm, Gardner pigment is less than grade 5, and acid value of fish oil after deacidification is less than 0.5mgKOH/g.

The ethylated fish oil is separated by molecular weight and the groups of molecules are evaporated under vacuum at temperatures running above the boiling point, with different average molecular free ranges for different components. Increase the temperature gradually to concentrate the fish oil in good status. The heating temperature must be carefully controlled to prevent overheating and degradation of the oil.

It’s important to note that short-path distillation is a complex process and requires specialized equipment design and operation expertise. It is best to consult with a professional or experienced technician before attempting short-path distillation. We are here to offer the cost effective equipment which have been working efficiently in most of GOED members and other fish oil refinery plants.

short path distillation equipment assembly
Multi-stages short path distillation columns assembly system for fish oil ester concentration.
  • Urea Saturation And Adsorption Separation:

It is a process used to refine and purify fish oil by removing impurities such as free fatty acids, phospholipids, and other polar compounds. The process involves treating the fish oil with urea and proper content of ethanol, the saturated fatty acid ethyl esters in fish oil are encapsulated in urea and then separated using the adsorption of urea onto saturated ethyl fish oil dissolved in ethanol, which forms complexes with the impurities, making them easier to remove.

The amount of urea used will depend on the specific fraction and content in the feed oil. The mixture is then heated to a specific temperature, typically around 70-80°C, for several hours to allow the urea to form complexes with the impurities in the oil.

The urea-treated fish oil is further purified to remove any remaining impurities such as heavy metals, PCBs, and other contaminants. This is typically done using a process called molecular distillation, which can separate the different components of the oil based on their boiling points.

  • Re-esterification:

Once the concentration process is complete, the concentrated Omega-3 can be re-esterified with anhydrous ethanol to create a stable and concentrated form of fish oil ester.

Deacidified fish oil is transesterified with ethanol, ethanol and sodium ethanol are taken and mixed well, added to the deacidified fish oil reaction kettle, the temperature is controlled at 40-70°C, stirred for 3-4hr, concentrated to recover ethanol and separated from glycerol after resting for 1-3hr, washed with water, dried under vacuum after stratification and dehydration to achieve an esterification rate of 98% or more.

Step 5: Fractionation by Chromatography

High-performance liquid chromatography (HPLC), argentometry, and supercritical fluids are chromatographic techniques utilized for the concentration of PUFA, specifically EPA & DHA to provide high-purity (over 95%) high purity products.

In general, the ethyl esters of fatty acids are the subject of argentometric chromatography separations, which occasionally combine preconcentration procedures before the final fractionation by chromatography.

The specific process flow shall be properly selected according to the specific feed quality and the desired purity level. Check here with detail process steps and project reference of solution for 97% content.


Once the concentration and refinement process is complete, the Omega-3 fish oil can be packaged into capsules, bottles, or other forms for distribution and consumption.

It is important to note that the quality and purity of the fish oil can vary depending on the source and processing methods used, Therefore, combining various techniques appears to be an effective solution for raising the purity and efficiency of these components.

So it is important to choose a reputable supplier that uses high-quality, sustainable process equipment and follows strict quality control standards. We are dedicated to working on the best solution for you.

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