What is olive oil
Olive oil is a fat obtained from the olive (the fruit of Olea europaea; family Oleaceae), a traditional tree crop of the Mediterranean Basin. The oil is produced by pressing whole olives.
It is commonly used in cooking, cosmetics, pharmaceuticals, and soaps and as a fuel for traditional oil lamps. Olive oil is used throughout the world, but especially in the Mediterranean countries and, in particular Greece, which has the highest consumption per person.
Extra Virgin Olive oil is produced by grinding olives and extracting the oil by mechanical means. For quality extra virgin olive oil care is taken to make sure the olives are perfectly ripened. The process is generally as follows:
The first step in the oil extraction process is cleaning the olives and removing the stems, leaves, twigs, and other debris left with the olives. The second step is crushing the olives into a paste. This step can be done with stone mills, metal tooth grinders, or various kinds of hammermills. Next step is malaxing (mixing) the paste for 20 to 45 minutes. This allows small oil droplets to combine into bigger ones. The most common mixer is a horizontal trough with spiral mixing blades. The final step consists in separating the oil from the rest of the olive components. Nowadays, this is usually done by centrifugation. Some centrifuges are called three-phase because they separate the oil, the water, and the solids separately. The two-phase centrifuges separate the oil from a wet paste.
The oil is then left in tanks or barrels where a final separation, if needed, happens through gravity. This is called racking the oil. Finally the oil can be filtered, if desired.
Olive Oil Production
The oil produced by only physical (mechanical) means as described above is called virgin oil. Extra virgin olive oil is virgin olive oil that satisfies specific high chemical and organoleptic criteria. Sometimes the oil will be filtered to eliminate remaining solid particles that may reduce the shelf life of the product. Labels may indicate the fact that the oil has not been filtered, suggesting a different taste.
The remaining paste (pomace) still contains a small quantity (about 5–10%) of oil that cannot be extracted by further pressing, but only with chemical solvents. The label term “cold-extraction” on extra virgin olive oils indicates that the olive grinding and stirring was done at a temperature of maximum 27 °C (77 °F), as treatment in higher temperatures risks decreasing the olive oils’ texture, taste and aroma.