How is extra virgin olive oil obtained?
Extra virgin olive oil is 100% natural juice, which preserves the aroma, flavor, 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 slightly more complicated process 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 at the same time as 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 avoid alterations.
The first step is the grinding. In a mill, the olive is crushed to break the cellular structures that contain the oil. It is basically 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 mixer, the olive paste is well mixed to homogenize the mixture and favor 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 re-centrifuge the oil at high speeds, and battery decanters are the most 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.