Olive oil is a liquid fat obtained from olives (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, whether for frying 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. It is associated with the “Mediterranean diet” for 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. Spain is the largest producer of olive oil, followed by Italy and Greece. However, per capita consumption is highest in Greece, followed by Spain, Italy, and Morocco. Consumption in North America and northern Europe is far less, but rising steadily.
The composition of olive oil varies with the cultivar, altitude, time of harvest and extraction process. It consists mainly of oleic acid (up to 83%), with smaller amounts of other fatty acids including linoleic acid (up to 21%) and palmitic acid (up to 20%). Extra-virgin olive oil is required to have no more than 0.8% free acidity and is considered to have favorable flavor characteristics; it forms as much as 80% of total production in Greece and 65% in Italy, but far less in other countries.
Olive oil is the main cooking oil in countries surrounding the Mediterranean, and it forms one of the three staple food plants of Mediterranean cuisine, the other two being wheat (as in pasta, bread, and couscous) and the grape, used as a dessert fruit and for wine.
Extra virgin olive oil is mostly used as a salad dressing and as an ingredient in salad dressings. It is also used with foods to be eaten cold. If uncompromised by heat, the flavor is stronger. It also can be used for sautéing.
The higher the temperature to which the olive oil is heated, the higher the risk of compromising its taste. When extra virgin olive oil is heated above 210–216 °C (410–421 °F), depending on its free fatty acid content, the unrefined particles within the oil are burned. This leads to deteriorated taste. Also, the pronounced taste of extra virgin olive oil is not a taste most people like to associate with their deep fried foods. Refined olive oils are perfectly suited for deep frying foods and should be replaced after several uses.
Choosing a cold-pressed olive oil can be similar to selecting a wine. The flavor of these oils varies considerably and a particular oil may be more suited for a particular dish.
An important issue often not realized in countries that do not produce olive oil is that the freshness makes a big difference. A very fresh oil, as available in an oil producing region, tastes noticeably different from the older oils available elsewhere. In time, oils deteriorate and become stale. One-year-old oil may be still pleasant to the taste, but it is less fragrant than fresh oil. After the first year, olive oil should be used for cooking, not for foods to be eaten cold, like salads.
The taste of the olive oil is influenced by the varietals used to produce the oil and by the moment when the olives are harvested and ground (less ripe olives give more bitter and spicy flavors – riper olives give a sweeter sensation in the oil).
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