How is extra virgin olive oil obtained?
Extra virgin olive oil is a 100% natural juice, which retains the aroma, taste, vitamins, and all the properties of the olive, being the only vegetable oil that can be consumed as it is obtained. It comes directly from olives, by squeezing them, although it is a process a little more complicated than squeezing an orange.
When the olive reaches the mill, the first thing that is done is to clean it, to separate it from impurities such as leaves and small branches that come off the tree along with the fruit. Once the olive is clean, it is ready to be crushed in the mill, this crushing consists basically of four steps. Throughout the process, both the olive and the oil are always in contact with inert material (stainless steel) to prevent alterations.
The first step is the grinding. In a mill, the olive is crushed to break the cellular structures that contain the oil. Basically, it is like putting the olive in a kitchen blender, but bigger. The result is the mass or paste of olives that are crushed olives with a mixture of bone and skin pieces, oil, and vegetation water.
The next step is the mixing. In a blender, the olive paste is mixed well to homogenize the mixture and promote the union of the small oil droplets into larger droplets. It is important that the mixing time does not exceed 90 minutes, and the temperature of the paste does not exceed 27 or 28 ºC.
Once mixed, the paste goes to centrifugation. In a decanter, the paste is centrifuged at high speed to separate the different components by difference in densities. In the cylindrical drum of the decanter, three concentric rings are formed with the different components. The pomace formed by the dry extract of the olive, bone and skin, with some moisture and a density around 1.2 gr/ml, forms the outermost ring. The vegetation water has a slightly higher density of 1 gr/ml, due to its dissolved components, and forms the intermediate ring. The oil, with a density of 0.92 gr/ml, forms the innermost ring.
The last step is the filtration. To remove the last impurities, different systems are used for this last step depending on the mill. Vertical centrifuges, which centrifuge the oil again at high speeds, and decanter batteries are the most commonly used systems. Some also use stainless steel mesh filters. Once clean of moisture and impurities, it is ready to go to the cellar to be packaged.