There are several ways to extract oil from plants and trees. For example, there is distillation and solvent extraction in which the plant is infused in other substances to extract the aromatic particles.
But when extracting oil from the seed, cold pressing is preferred. This process is used for most carrier oils and many essential oils. This process ensures that the resulting oil is 100% pure and retains all the properties of the plant.
Why it it cold pressed?
The cold pressing process does not need an external substance as with other methods. The seeds are crushed and pressed in order to force the oil out.
Though the friction caused by the pressure does increase the temperature of the product, this is not high. Manufacturers must keep it within a certain degree range to be able to claim that the oil is cold pressed. For instance, to obtain jojoba oil without damaging the properties it cannot exceed 45 ° C. The extra virgin olive oil we use for cooking cannot exceed 25 °.
What are the steps?
1. The process begins with the filtering stage, in which the seeds will be passed through a series of spaces with air propulsion systems. This process removes any impurities.
2. Milling: The nuts, seeds, or fruits are ground into a paste using heavy granite millstones or modern stainless steel presses, which are found in large commercial operations.
3. Pressing: The semi-solid paste is slowly stirred, often with a rotating screw which encourages the oil to separate from the solid parts and clump together. Once this happens, pressure is applied to force the oil out. It is one of the most important moments of the whole process, since this pressure may increase the temperature of the dough. If it exceeds a certain temperature, the oil may lose some of its properties.
4. Filtering: The pressed oil goes through a series of filters that separate small pieces of peel or pulp of the fruit from the oil. The final part of this filtering process involves passing the oil through a cloth or paper to ensure that all impurities are removed from the oil.
This method of oil extraction requires the use a lot of fruits and seeds (e.g. for one litre of Argan oil up to 30 kg of seeds will be used), the discarded parts do not go to waste, they are used for animal feeds or fertilizers.
5. Once the filtering process is complete, a decantation process is carried out. Any remaining sedement is separated from the oil by the simple force of gravity. Thus, a 100% pure and natural oil that retains all its properties will be obtained.