Olive oil is a fruit oil obtained from the olive, a traditional tree crop of the Mediterranean Basin. The wild olive tree originated in Asia Minor and spread from there as far as southern Africa, Australia, Japan and China. 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.
Over 750 million olive trees are cultivated worldwide, 95% of which are in the Mediterranean region. Most of global production comes from Southern Europe, North Africa and the Middle East.
Olive oil is produced by grinding olives and extracting the oil by mechanical or chemical means. Green olives produce bitter oil, and overripe olives produce rancid oil, so for good extra virgin olive oil care is taken to make sure the olives are perfectly ripened.
First the olives are ground into paste using large millstones or steel drums.If ground with mill stones, the olive paste generally stays under the stones for 30–40 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, since oil has a lower specific weight than water. This very slow separation process has been replaced by centrifugation, which is much faster and more accurate. 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 micro organisms. 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.
The oil produced by only mechanical means as described is called virgin oil. Extra virgin olive oil is virgin olive oil that satisfies specific high chemical and organoleptic criteria suchs as low free acidity, no or very little organoleptic defects. 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.
There is a large body of clinical data to show that consumption of olive oil can provide heart health benefits such as favourable effects on cholesterol regulation and LDL cholesterol oxidation, and that it exerts antiinflamatory, antithrombotic, antihypertensive as well as vasodilatory effects both in animals and in humans.
World production in 2002 was 2.6 million tons, of which Spain contributed 40% to 45%. In 2006, Turkey accounted for about 5% of world production, similar to the Spanish province of Jaén alone, well known for the biggest olive groves in the world. Of the European production, 93% comes from Spain, Italy, Greece.