Sunflower oil refining technologies: how to improve its quality and shelf life

Various types of vegetable oils, including sunflower oil, can be refined or unrefined. Both types of this product are obtained from the same raw material, but different methods are used to extract oil from it and further processing. In the case of unrefined, it is cold or hot pressing, and in the case of refined, it can be also solvent extraction. In addition, refined oil undergoes several stages of processing and purification using a comprehensive vegetable oil refining and deodorization line that includes various types of specialized equipment, while unrefined oil undergoes only mechanical filtration.

What is oil refining?

Refining is the process of purifying a substance from undesirable impurities. In case of vegetable oil, it means removing undesirable non-fat, organoleptic and other types of impurities using various purification methods:

• physical
• chemical
• combination of physical and chemical.

 Each of these methods removes different types of impurities from the oil.

Advantages of sunflower oil refining

When sunflower oil is extracted from sunflower seeds, natural components of the seeds and other undesirable impurities get into the oil. Their presence in the product is the reason for its opacity and coloration, as well as the appearance of odor and carbon deposits on heated contact surfaces. This can be avoided by the refining process. Speaking about the advantages of refined oil, we can highlight the following advantages:

• It has a much longer shelf life than unrefined oil;
• It becomes much lighter, reducing the possibility of sedimentation;
• no odor or taste.

In addition, when fried in a pan, refined oil does not smoke or foam, and does not emit harmful cancer-causing substances.

Main stages of sunflower oil refining

Each refinery uses a different refined oil production scheme. However, in any case, although in different combinations, it includes the following stages

• mechanical purification (filtration)
• water degumming
• neutralization
• adsorption treatment (bleaching);
• Winterization (freezing);
• deodorization.

To make the product completely odorless and tasteless, it is subjected to steam treatment. This process is called deodorization.

The process of water degumming

After the sunflower seed kernels were crushed, the resulting oil cake was roasted on special cookers for the oil mill, and the oil was extracted and purified from mechanical impurities, settled and filtered, it is then subjected to a water degumming process. This is the name given to the process of treating the resulting oil with orthophosphoric acid. During this process, phosphorus-containing substances become hydrated, and after mixing the oil with water, the remaining phosphatide residues are removed in a separator. If this is not done, the finished product will quickly spoil.

The process of neutralization

After water degumming, the oil is treated with a citric acid solution and alkalis. This process is called neutralization or alkaline refining. Alkalis neutralize free fatty acids, which in turn help to remove pesticides and heavy metals from the mixture. This slows down the oxidation of the product, which increases its shelf life.

The process of bleaching

The adsorption treatment of sunflower oil, or its bleaching, involves exposing the fatty mixture to organic adsorbents. This measure is necessary to lighten the product by purifying it from carotenoids (coloring pigments). Absorbent treatment also helps to eliminate a certain amount of peroxide compounds and phosphorus-containing substances.

The process of winterization

Freezing the oil, known as winterization, is the final step in making the finished product free of any color. This process involves

• slow cooling of the oil;
• keeping it at a low positive temperature;
• removal of the wax-containing sediment by filtration.

Various types of heat exchangers are used in the winterization process.

Deodorization process

The final stage of oil refining is its deodorization, i.e. exposure of the product to steam (its temperature should be approximately 220 degrees). This measure improves the flavor and stability of the oil, completely removes the odor, and extends the shelf life.

New technologies in oil refining

To minimize the amount of waste and oil loss, reduce the consumption of reagents and other auxiliary materials, refineries are gradually switching to new, more cost-effective technologies such as cold neutralization, physical refining, and cold enzyme hydration.

Methods of oil quality improvement

To improve the quality of sunflower oil, along with the use of new technologies, the method of artificially saturating a conventional refined product with additional components in the form of antioxidants is used.

Monitoring and quality control

To ensure that the quality of vegetable oils produced in Ukraine meets international standards, finished products are tested in measuring laboratories equipped with modern instruments and comprehensive test systems. TAN manufactures various types of processing lines and a full range of equipment for the production of vegetable oils and their refining.