page_title: Olive oil
section_title: Extraction
hierarchical_section_title: Olive oil / Extraction
caption_attribution_description: English: A cold press olive oil machine at Saba Habib manufacturers in Kibbutz Parud in palestine.
context_page_description: Olive oil is a liquid fat obtained from olives, a traditional tree crop of the Mediterranean Basin, produced by pressing whole olives and extracting the oil. Olive oil is the most common vegetable oil. It is commonly used in cooking, for frying foods or as a salad dressing. It is also used in cosmetics, pharmaceuticals, and soaps, and as a fuel for traditional oil lamps, and has additional uses in some religions. There is limited evidence of its possible health benefits. The olive is one of three core food plants in Mediterranean cuisine; the other two are wheat and grapes. Olive trees have been grown around the Mediterranean since the 8th millennium BC.
  The top five producers of olive oil by volume are Spain, Morocco, Turkey, Greece, and Italy. However, per capita national consumption is highest in Greece, followed by Spain and Italy.
  The composition of olive oil varies with the cultivar, altitude, time of harvest and extraction process. It consists mainly of oleic acid, with smaller amounts of other fatty acids including linoleic acid and palmitic acid.
context_section_description: Olive oil is produced by grinding olives and extracting the oil by mechanical or chemical means. Green olives usually produce more bitter oil, and overripe olives can produce oil that is rancid, so for good extra virgin olive oil care is taken to make sure the olives are perfectly ripened. The process is generally as follows:
  The olives are ground into paste using large millstones (traditional method) or steel drums (modern method).
  If ground with mill stones, the olive paste generally stays under the stones for 30 to 40 minutes. A shorter grinding process may result in a more raw paste that produces less oil and has a less ripe taste, a longer process may increase oxidation of the paste and reduce the flavor. After grinding, the olive paste is spread on fiber disks, which are stacked on top of each other in a column, then placed into the press. Pressure is then applied onto the column to separate the vegetal liquid from the paste. This liquid still contains a significant amount of water. Traditionally the oil was shed from the water by gravity (oil is less dense than water). This very slow separation process has been replaced by centrifugation, which is much faster and more thorough. The centrifuges have one exit for the (heavier) watery part and one for the oil. Olive oil should not contain significant traces of vegetal water as this accelerates the process of organic degeneration by microorganisms. The separation in smaller oil mills is not always perfect, thus sometimes a small watery deposit containing organic particles can be found at the bottom of oil bottles.
  In modern steel drum mills the grinding process takes about 20 minutes. After grinding, the paste is stirred slowly for another 20 to 30 minutes in a particular container (malaxation), where the microscopic oil drops aggregate into bigger drops, which facilitates the mechanical extraction. The paste is then pressed by centrifugation/ the water is thereafter separated from the oil in a second centrifugation as described before.
  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 (low free acidity, no or very little organoleptic defects). A higher grade extra virgin olive oil is mostly dependent on favourable weather conditions; a drought during the flowering phase, for example, can result in a lower quality (virgin) oil. It is worth noting that olive trees produce well every couple of years, so greater harvests occur in alternate years (the year in-between is when the tree yields less). However the quality is still dependent on the weather.
  Sometimes the produced 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. Fresh unfiltered olive oil usually has a slightly cloudy appearance, and is therefore sometimes called cloudy olive oil. This form of olive oil used to be popular only among small scale producers but is now becoming "trendy", in line with consumer's demand for products that are perceived to be less processed. But generally, if not tasted or consumed soon after production, filtered olive oil should be preferred: "Some producers maintain that extra-virgin olive oils do not need filtration but also that filtration is detrimental to oil quality. This point of view should be considered as erroneous and probably the result of improper implementation of this operation. In fact, fine particles that are suspended in a virgin olive oil, even after the most effective centrifugal finishing, contain water and enzymes that may impair oil stability and ruin its sensory profile. [...] Filtration makes an extra-virgin olive oil more stable and also more attractive. If the suspended particles are not removed they slowly agglomerate and flocculate, forming a deposit on the bottom of the storage containers. Such a deposit continues to be at risk of enzymatic spoilage and, in 
caption: A cold press olive oil machine in Israel.
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