Olive Oil
| Infobox on Olive Oil | |
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| Example of Olive Oil |  |
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| Humidity / moisture | - |
| Ventilation | See text |
| Risk factors | See text |
Olive Oil
Description / Application
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 grinding whole olives and extracting the oil by mechanical or chemical means.
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, in Greece, which has the highest consumption per person.
Among the many different olive varieties or List of olive cultivars there are: in Greece Koroneiki, Lianolia, Chondrolia (a.k.a. Throumbolia), Tsounati, Patrinia and more.
In Spain, the most important varieties are the Picual, Arbequina, Hojiblanca, and Manzanillo de Jaén; In Italy, Frantoio, Leccino Pendolino, and Moraiolo; in France, Picholine; in California, Mission; in Portugal, Galega, Verdeal and Cobrançosa; in Croatia, Oblica and Leccino. The oil from the varieties varies in flavour and stability.
Commercial grades
- All production begins by transforming the olive fruit into olive paste. This paste is then malaxed (slowly churned or mixed) to allow the microscopic oil droplets to concentrate. The oil is extracted by means of pressure (traditional method) or centrifugation (modern method). After extraction the remnant solid substance, called pomace, still contains a small quantity of oil.
The grades of oil extracted from the olive fruit can be classified as:
- Virgin means the oil was produced by the use of physical means and no chemical treatment. The term virgin oil referring to production is different from Virgin Oil on a retail label (see next section).
- Refined means that the oil has been chemically treated to neutralize strong tastes (characterized as defects) and neutralize the acid content (free fatty acids). Refined oil is commonly regarded as lower quality than virgin oil; oils with the retail labels extra-virgin olive oil and virgin olive oil cannot contain any refined oil.
- Olive pomace oil means oil extracted from the pomace using solvents, mostly hexane, and by heat.
- Quantitative analysis can determine the oil's acidity, defined as the percent, measured by weight, of free oleic acid it contains. This is a measure of the oil's chemical degradation; as the oil degrades, more fatty acids are freed from the glycerides, increasing the level of free acidity and thereby increasing rancidity. Another measure of the oil's chemical degradation is the organic peroxide level, which measures the degree to which the oil is oxidized, another cause of rancidity.
- To classify it by taste, olive oil is subjectively judged by a panel of professional tasters in a blind taste test. This is also called its organoleptic quality.
Retail grades in IOC member nations
- In countries that adhere to the standards of the International Olive Council (IOC) the labels in stores show an oil's grade.
- Extra-virgin olive oil comes from virgin oil production only, contains no more than 0.8% acidity, and is judged to have a superior taste. 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: 45%, Spain 30%). It is used on salads, added at the table to soups and stews and for dipping.
- Virgin olive oil comes from virgin oil production only, has an acidity less than 1.5%, and is judged to have a good taste.
- Pure olive oil Oils labeled as Pure olive oil or Olive oil are usually a blend of refined and virgin production oil.
- Olive oil is a blend of virgin and refined production oil, of no more than 2% acidity. It commonly lacks a strong flavour.
- 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 flavor 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.
- Lampante oil is olive oil not suitable as food; lampante comes from olive oil's long-standing use in oil-burning lamps. Lampante oil is mostly used in the industrial market.
- 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 and/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.
Extraction
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:
1. The olives are ground into paste using large millstones (traditional method) or steel drums (modern method).
2. 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.
3. 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).
4. 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. Unfiltered fresh olive oil that has a slightly cloudy appearance is 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 more ecological and less-processed "green" products.
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).}}