After the olives are collected, the leaves, shells are removed, washed and ready to be squeezed. In old times, stone or granite wheels were used for spinning. Today, cylinders made of stainless steel crush the olives and make them into dough. This olive dough is then subjected to kneading. Water is slowly added to the olive paste. This process brings together the fat molecules.
The dough is kneaded for 20 to 40 minutes. If the process lasts longer, there is less risk of fat and there is a risk that other flavors will be mixed with the oil. In addition, because they will come in contact with air, free radicals are also released which may affect the quality of the oil.
In modern systems, tanks are filled with a harmless gas to prevent oxidation for kneading. This method increases the amount of oil and flavor that will be released and maintains the quality of the oil. The mixture can be heated to 27-28 degrees to increase the amount of oil to be released, but this causes a little oxidation. This temperature is called "cold pressed".
After the kneading process, the dough is either slightly tightened or placed in the centrifuge machine. When the machine rotates at high speed, water and oil accumulate in the middle chamber. The oil and water are then separated.
After the oil is removed, there is some oil in the remaining posa. Some manufacturers use steam, hexane or other solvents to remove residual oil. It should be noted that this low quality oil is prin oil.
The oil can then be refined, bleached and / or deodorized. Refining reduces acidity and bitterness. In the bleaching process, chlorophyll and carotenoids (pigments that give color to the plants) and possible pesticide residues are cleared and a lighter colored oil with less nutrients appears. Deodorization also removes the sharp smell of olive oil.
The oil is stored in stainless steel tanks at about 18 degrees in factories to ensure that the oil is not damaged before being bottled and transported.