Olives and Olive Oil
The olive, known by the botanical name olea europaea, meaning "European olive" is a species of small tree in the family oleaceae, found in much of Africa, the Mediterranean basin from Portugal to the levant, the Arabian peninsula and southern Asia as far east as china, as well as the canary islands, Mauritius and réunion. The species is cultivated in many places and considered naturalized in all the countries of the Mediterranean coast, as well as in Argentina, Saudi Arabia, java, Norfolk island, California and Bermuda. Olea europeana sylvestris is a subspecies that corresponds to a smaller tree bearing noticeably smaller fruits.
The olive's fruit, also called the olive, is of major agricultural importance in the Mediterranean region as the source of olive oil; it is one of the coreingredients in Mediterranean cuisine. The tree and its fruit give their name to the plant family, which also includes species such as lilacs, jasmine, forsythia and the true ash trees (fraxinus). The word derives from Latin ŏlīva ("olive fruit" "olive tree" "olive oil" is ŏlĕum) a borrowing from the Greek ἐλαία (elaía, "olive fruit" "olive tree") and ἔλαιον (élaion, "olive oil") the word "oil" in multiple languages ultimately derives from the name of this tree and its fruit.
The olive tree, olea europaea, has been cultivated for olive oil, fine wood, olive leaf, and the olive fruit. 90% of all harvested olives are turned into oil, while about 10% are used as table olives. The olive is one of the "trinity" or "triad" of basic ingredients in Mediterranean cuisine, the other two being wheat for bread, pasta and couscous, and the grape for wine.
Table olives are classified by the ioc into 3 groups according to the degree of ripeness achieved before harvesting:
Green olives. Picked when they have obtained full size, but before the ripening cycle has begun. Usually shades of green to yellow.
Semi-ripe or turning-colour olives. Picked at the beginning of the ripening cycle, when the colour has begun to change from green to multi-colour shades of red to brown. Only the skin is coloured as the flesh of the fruit lacks pigmentation at this stage, unlike that of ripe olives.
Black olives or ripe olives. Picked at full maturity when fully ripe. Found in assorted shades of purple to brown to black.
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 and is commonly used in cooking, cosmetics, pharmaceuticals, and soaps, and as a fuel for traditional oil lamps. Olive oil is used throughout the world and is often associated with Mediterranean cuisine and diet.
There are many different olive varieties or olives, each with a particular flavour, texture, and shelf life that make them more or less suitable for different applications such as direct human consumption on bread or in salads, indirect consumption in domestic cooking or catering, or industrial uses such as animal feed or engineering applications.
Extra-virgin olive oil comes from virgin oil production only, and is of higher quality: among other things, it contains no more than 0.8% free acidity, and is judged to have a superior taste, having some fruitiness and no defined sensory defects. Extra-virgin olive oil accounts for less than 10% of oil in many producing countries; the percentage is far higher in the Mediterranean countries (Greece: 80%, Italy: 65%, Spain 50%).
Virgin olive oil comes from virgin oil production only, but is of slightly lower quality, with free acidity of up to 1.5%, and is judged to have a good taste, but may include some sensory defects.
Refined olive oil is the olive oil obtained from virgin olive oils by refining methods that do not lead to alterations in the initial glyceridic structure. It has a free acidity, expressed as oleic acid, of not more than 0.3 grams per 100 grams (0.3%) and its other characteristics correspond to those fixed for this category in this standard. This is obtained by refining virgin olive oils with a high acidity level or organoleptic defects that are eliminated after refining. Note that no solvents have been used to extract the oil, but it has been refined with the use of charcoal and other chemical and physical filters. Oils labeled as pure olive oil or olive oil are primarily refined olive oil, with a small addition of virgin-production to give taste.
Olive pomace oil is refined pomace olive oil often blended with some virgin oil. It is fit for consumption, but may not be described simply as olive oil. It has a more neutral flavour than pure or virgin olive oil, making it unfashionable among connoisseurs; however, it has the same fat composition as regular olive oil, giving it the same health benefits. It also has a high smoke point, and thus is widely used in restaurants as well as home cooking in some countries.
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 flavour. After grinding, the olive paste is spread on fibre 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 unite 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 olive oil small scale producers but is now becoming "trendy", in line with consumer's demand for products that are perceived to be less processed.
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. This is done in specialised chemical plants, not in the oil mills. The resulting oil is not "virgin" but "pomace oil". The term "first press", sometimes found on bottle labels, is today meaningless, as there is no "second" press; it comes from ancient times of stone presses, when virgin oil was the one produced by battering the olives.
The label term "cold-extraction" on extra virgin olive oils indicates that the olive grinding and stirring was done at a temperature of maximum 25 °c (77 °f), as treatment in higher temperatures risks decreasing the olive oils' quality (texture, taste and aroma).