How is sunflower oil produced?

The vegetable oil of sunflower is derived from sunflower seeds. Each year, approximately 16 million tonnes of oil is produced globally. The oldest method of extraction is cold pressing. This process begins with the harvesting and cleaning of the sunflower husks. These are then shelled to extract the seeds. After a thorough cleaning and drying, they are introduced into an oil press. Within the press, the seeds are mechanically compressed. This gentle pressure crushes the cells of the seeds, thereby releasing the oil they contain. The heat generated by the pressure is minimal.

Once the oil is extracted, it is separated from solid residues and hydrophilic compounds by centrifugation. Impurities such as colloidal matter, phospholipids, excess free fatty acids (FFA) and colouring agents are thus removed. The resulting oil is then filtered to eliminate the last unwanted particles. Cold pressing results in a high-quality sunflower oil, referred to as "virgin" or "extra-virgin", which retains its natural colour and properties. This oil can be used in the food industry or in cosmetics.

• Benefits : This is a completely natural and minimally polluting extraction method, which does not require the use of a chemical solvent. It is therefore environmentally friendly and uses relatively little energy. Moreover, it allows the preservation of the active ingredients and the quality of the oil as it takes place at a low temperature. This extraction method makes the oil more resistant to rancidity.

• Drawbacks : The yield obtained from cold pressing is relatively low compared to the use of other techniques such as solvent extraction.

Note: At Typology, we use cold-pressed sunflower oil for the formulation of our skincare products.

The solvent extraction method involves applying moderate pressure to the seed to extract the majority of the oil before using a solvent. This second step allows the separation of additional oil from the solid fraction. In practice, the seeds are placed in an extractor containing the solvent. This is most often hexane, an organic solvent. The oil, being miscible in this solvent, will then dissolve in it.

The mixture is then placed into an evaporator and heated to allow the solvent to evaporate. Following this, the obtained sunflower oil is refined to remove impurities. The solvent extraction process is the most widely used treatment method in the world today for the extraction of sunflower oil.

• Benefits : Solvent extraction allows for a significant yield, potentially reaching up to 97%.

• Drawbacks : Solvent extraction requires a significant volume of solvents. Solvents are typically expensive and polluting compounds, posing a risk to the environment. They can also represent a real public health issue and have harmful effects on health, particularly on reproduction.

The supercritical CO2 extraction method is a relatively recent and somewhat lesser-known process. However, it is a technique that utilises a fairly simple process. Indeed, this method is based on the use of a gas, CO2, which, when it enters a so-called "supercritical" state, possesses properties that lie between those of a gas and those of a liquid. It then exhibits a significant extraction capacity.

To carry out this type of extraction, a stream of CO2 in a supercritical state is sent through an extractor containing sunflower seeds. It then becomes charged with oil, and transitions into a gaseous phase which allows the separation of CO2 and the oil, in a device called a "separator".

• Benefits : The supercritical CO2 extraction method is relatively gentle. It allows for the preservation of all the properties of the vegetable oil and does not generate any harmful waste. Moreover, CO2 is a non-toxic natural gas and is abundantly available in the industrial world.

• Drawbacks : The equipment required to perform an extraction by CO2 supercritical is relatively expensive.

The enzyme extraction method is also relatively recent. It is based on the use of enzymes such as cellulases or glucosidases. These enzymes facilitate the execution of a mechanical extraction by hydrolysis of lipoproteins, namely the lipopolysaccharides and polysaccharides contained in the cell wall. This hydrolysis allows for the complete release of the vegetable oil. To carry out this method, the use of a mixture of enzymes is necessary as it ensures the degradation of all unwanted particles and the extraction of all the oil.

The enzyme extraction process unfolds as follows: sunflower seeds are placed within a grinder to reduce their size and thus increase the contact surface available with the enzymes. The mixture is then placed in a tank where the stage of enzymatic hydrolysis takes place. Finally, following this phase, the products are placed in a separator that centrifuges the mixture to separate the different parts and obtain only the vegetable oil.

• Benefits : The enzyme extraction method allows for a high yield of extraction. Moreover, it is relatively quick, requires little solvent, and poses no environmental issues.

• Drawbacks : The costs of enzymes and production are high.

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