Not to be confused with the cartoon character
Olive Oyl.
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.
Olive "trapetum" (crusher) in Pompeii (79 AD)
General chemical structure of olive oil (
triglyceride). R
1, R
2 and R
3 are
alkyl groups (approx. 20%) or alkenyl groups (approx. 80%).
The olive tree is native to the Mediterranean basin; wild olives were collected by Neolithic peoples as early as the 8th millennium BC.[1] The wild olive tree originated in Asia Minor[2] in modern Greece.
It is not clear when and where olive trees were first domesticated: in Asia Minor in the 6th millennium; along the Levantine coast stretching from the Sinai Peninsula to modern Turkey in the 4th millennium;[1] or somewhere in the Mesopotamian Fertile Crescent in the 3rd millennium.
A widespread view exists that the first cultivation took place on the island of Crete. Archeological evidence suggest that olives were being grown in Crete as long ago as 2,500 B.C. The earliest surviving olive oil amphorae date to 3500 BC (Early Minoan times), though the production of olive is assumed to have started before 4000 BC. An alternative view retains that olives were turned into oil by 4500 BC by Canaanites in present-day Israel.[3]
Ancient oil press
Bodrum Museum of Underwater Archaeology, Bodrum, Turkey
Homer called it "liquid gold." In ancient Greece, athletes ritually rubbed it all over their bodies. Olive oil has been more than mere food to the peoples of the Mediterranean: it has been medicinal, magical, an endless source of fascination and wonder and the fountain of great wealth and power. Indeed the importance of the olive industry in ancient economies cannot be overstated. The tree is extremely hardy and its useful lifespan can be measured in centuries. Its wide and deep root system ensures its survival without additional watering, even in the water-sparse Mediterranean. It thrives close to the sea, where other plants cannot tolerate the increased salt content of underground water. Other than pruning in late spring, it needs minimal cultivation and its fruit matures in the late autumn in the Northern Mediterranean or through the winter (further south), when other staple food harvests are over and there is no other agricultural work to be done. Olive collecting and processing is relatively straightforward, and needs minimal, mechanical technology. Olive oil, being almost pure fat, is dense in calories yet healthy, without adverse health effects. Unlike cereals which can be destroyed by humidity and pests in storage, olive oil can be very easily stored and will not go rancid for at least a year (unless needlessly exposed to light or extremely hot weather), by which time a fresh harvest will be available. The combination of these factors helped ensure that the olive industry has become the region's most dependable food and cash crop since prehistoric times.
Besides food, olive oil has been used for religious rituals, medicines, as a fuel in oil lamps, soap-making, and skin care application. The importance and antiquity of olive oil can be seen in the fact that the English word oil derives from c. 1175, olive oil, from Anglo-Fr. and O.N.Fr. olie, from O.Fr. oile (12c., Mod.Fr. huile), from L. oleum "oil, olive oil" (cf. It. olio), from Gk. elaion "olive tree",[4] which may have been borrowed through trade networks from the Semitic Phoenician use of el'yon meaning "superior", probably in recognized comparison to other vegetable or animal fats available at the time. Robin Lane Fox suggests[5] that the Latin borrowing of Greek elaion for oil (Latin oleum) is itself a marker for improved Greek varieties of oil-producing olive, already present in Italy as Latin was forming, brought by Euboean traders, whose presence in Latium is signaled by remains of their characteristic pottery, from the mid-eighth century.
Recent genetic studies suggest that species used by modern cultivators descend from multiple wild populations, but a detailed history of domestication is not yet understood.[6]
Many ancient presses still exist in the Eastern Mediterranean region, and some dating to the Roman period are still in use today.[citation needed]
Over 5,000 years ago oil was being extracted from olives in the Eastern Mediterranean. In the centuries that followed, olive presses became common, from the Atlantic shore of North Africa to Persia and from the Po Valley to the settlements along the Nile.[citation needed]
Olive trees and oil production in the Eastern Mediterranean can be traced to archives of the ancient city-state Ebla (2600–2240 BC), which were located on the outskirts of the Syrian city Aleppo. Here some dozen documents dated 2400 BC describe lands of the king and the queen. These belonged to a library of clay tablets perfectly preserved by having been baked in the fire that destroyed the palace. A later source is the frequent mentions of oil in Tanakh.[citation needed]
Dynastic Egyptians before 2000 BC imported olive oil from Crete, Syria and Canaan and oil was an important item of commerce and wealth. Remains of olive oil have been found in jugs over 4,000 years old in a tomb on the island of Naxos in the Aegean Sea. Sinuhe, the Egyptian exile who lived in northern Canaan about 1960 BC, wrote of abundant olive trees.[7]
Until 1500 BC, eastern coastal areas of the Mediterranean were most heavily cultivated. Olive trees were certainly cultivated by the Late Minoan period (1500 BC) in Crete, and perhaps as early as the Early Minoan.[8] The cultivation of olive trees in Crete became particularly intense in the post-palatial period and played an important role in the island's economy. The Minoans used olive oil in religious ceremonies. The oil became a principal product of the Minoan civilization, where it is thought to have represented wealth. The Minoans put the pulp into settling tanks and, when the oil had risen to the top, drained the water from the bottom.[citation needed] Olive tree growing reached Iberia and Etruscan cities well before the 8th century BC through trade with the Phoenicians and Carthage, then spread into Southern Gaul by the Celtic tribes during the 7th century BC.
The first recorded oil extraction is known from the Hebrew Bible and took place during the Exodus from Egypt, during the 13th century BC. During this time, the oil was derived through hand-squeezing the berries and stored in special containers under guard of the priests. A commercial mill for non-sacramental use of oil was in use in the tribal Confederation and later in 1000 BC, the fertile crescent, and area consisting of present day Palestine, Lebanon, and Israel. Over 100 olive presses have been found in Tel Miqne (Ekron), where the Biblical Philistines also produced oil. These presses are estimated to have had output of between 1,000 and 3,000 tons of olive oil per season.
Olive trees were planted in the entire Mediterranean basin during evolution of the Roman republic and empire. According to the historian Pliny, Italy had "excellent olive oil at reasonable prices" by the first century AD, "the best in the Mediterranean", he maintained, a claim probably disputed by many ancient olive growers. Thus olive oil was very common in Hellene and Latin cuisine. According to Herodotus, Apollodorus, Plutarch, Pausanias, Ovid and more, the city of Athens obtained its name because Athenians considered olive oil essential, preferring the offering of the goddess Athena (an olive tree) over the offering of Poseidon (a spring of salt water gushing out of a cliff).
The Spartans were the Hellenes who used oil to rub themselves while exercising in the gymnasia. The practice served to eroticise and highlight the beauty of the male body. From its beginnings early in the seventh century BC, the decorative use of olive oil quickly spread to all of Hellenic city states, together with naked appearance of athletes, and lasted close to a thousand years despite its great expense.[9][10]
Among the many different olive varieties or List of olive cultivars there are: in Greece Koroneiki, Lianolia, Chondrolia (a.k.a. Throumbolia), Tsounati, Patrinia olive and more.
In Spain, the most important varieties are the Picual, Arbequina, Hojiblanca, and Manzanillo de Jaén; in France, Picholine; in California, Mission; in Portugal, Galega; in Croatia, Oblica and Leccino. The oil from the varieties varies in flavour and stability (shelf life).[citation needed]
In Italy, Frantoio, Leccino Pendolino, and Moraiolo are the most famous varieties of cultivars.
Three countries are the major olive oil producers in the world. First is Spain, second is Italy and third is Greece. Together, they produce more than 75% of the world production.[11] In Italy the major producers are called "Città dell'Olio", "oil cities"; some of the most important are Lucca, whose oil is widely considered the best for acidity and stability, and traditionally used by oil merchant as a term of comparison,[12] Florence and Siena, in Tuscany. However the largest production is harvested in Puglia. The highest quality of Spanish olive Oil comes from the Les Borges Blanques region (province of Lleida), in Catalonia. Portugal accounts for 5% of the worlds production and its main export market is Brazil.
Australia now produces a substantial amount of olive oil. Many Australian producers only make premium oils, while a number of corporate growers operate groves of a million trees or more and produce oils for the general market. Australian olive oil is exported to Asia, Europe and the United States.[13]
In North America, Italian and Spanish olive oils are the best-known, and top-quality extra-virgin oils from Italy, Spain, Portugal and Greece are sold at high prices, often in "prestige" packaging. A large part of U.S. olive oil imports come from Italy, Spain, and Turkey. The U.S. imported 47,800,000 US gallons (181,000 m3) of olive oil in 1998, of which 34,600,000 US gallons (131,000 m3) came from Italy.[14]
New Zealand, The Republic of South Africa,[15] Argentina[16] and Chile[17] also produce extra virgin olive oil.
Olive orchards in Arizona, California, and Texas are producing olive oil that is appearing on USA grocery market shelves along side the Mediterranean olive oils.
International Olive Oil Council building
The International Olive Council (IOC) is an intergovernmental organization based in Madrid, Spain, with 23 member states.[18] It promotes olive oil around the world by tracking production, defining quality standards, and monitoring authenticity. More than 85% of the world's olives are grown in IOC member nations. The United States is not a member of the IOC, and the U.S. Department of Agriculture does not legally recognize its classifications (such as extra-virgin olive oil). The USDA uses a different system, which it defined in 1948 before the IOC existed. On October 25, 2010, the United States adopted new olive oil standards, a revision of those that had been in place since 1948, which affect importers and domestic growers and producers by ensuring conformity with the benchmarks commonly accepted in the U.S. and abroad.[19]
Olive oil is classified by how it was produced, by its chemistry, and by panels that perform olive oil taste testing.[20] The IOC officially governs 95% of international production and holds great influence over the rest. The EU regulates the use of different protected designation of origin labels for olive oils.[21]
U.S. Customs regulations on "country of origin" state that if a non-origin nation is shown on the label, then the real origin must be shown on the same side of the label and in comparable size letters so as not to mislead the consumer.[22][23] Yet most major U.S. brands continue to put "imported from Italy" on the front label in large letters and other origins on the back in very small print.[24] "In fact, olive oil labeled 'Italian' often comes from Turkey, Tunisia, Morocco, Spain, and Greece."[25] These products are a mixture of olive oil from more than one nation and it is not clear what percentage of the olive oil is really of Italian origin. This practice makes it difficult for high quality, lower cost producers outside of Italy to enter the U.S. market, and for genuine Italian producers to compete.
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.
Italian label for "extra vergine" oil
In countries that adhere to the standards of the IOC[26] 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 flavor.
- 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, rendering 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.
As the United States is not a member, the IOC retail grades have no legal meaning in that country; terms such as "extra virgin" may be used without legal restrictions but as of October 25, 2010, the U.S. Standards for Grades of Olive Oil and Olive-Pomace Oil went into effect.[27] The U.S. Department of Agriculture (USDA) currently has a four-part grading of olive oil based on acidity, absence of defects, odor and flavor:[27]
- U.S. Extra Virgin Olive Oil for oil with excellent flavor and odor and free fatty acid content of 0.8g per 100g (0.8%);
- U.S. Virgin Olive Oil for oil with reasonably good flavor and odor and free fatty acid content of not more than 2g per 100g (2%);
- U.S. Virgin Olive Oil Not Fit For Human Consumption Without Further Processing is a virgin oil of poor flavor and odor;
- U.S. Olive Oil is an oil mix of both virgin and refined oils;
- U.S. Refined Olive Oil is an oil made from refined oils with some restrictions on the processing;
These grades are voluntary. Certification is available from the USDA on a fee-for-service basis.[27]
The U.S. Department of Agriculture (USDA) previously listed four grades of olive oil. These grades were established in 1948, and are based on acidity, absence of defects, odor and flavor:[27]
- U.S. Grade A or U.S. Fancy possesses a free fatty acid content of not more than 1.4% and is "free from defects";
- U.S. Grade B or U.S. Choice possesses a free fatty acid content of not more than 2.5% and is "reasonably free from defects";
- U.S. Grade C or U.S. Standard possesses a free fatty acid content of not more than 3.0% and is "fairly free from defects";
- U.S. Grade D or U.S. Substandard possesses a free fatty acid content greater than 3.0% and "fails to meet the requirements of U.S. Grade C".
These grades are entirely voluntary and are available from the USDA on a fee-for-service basis.[27]
- The different names for olive oil indicate the degree of processing the oil has undergone as well as the quality of the oil. Extra-virgin olive oil is the highest grade available, followed by virgin olive oil. The word "virgin" indicates that the olives have been pressed to extract the oil; no heat or chemicals have been used during the extraction process, and the oil is pure and unrefined. Virgin olive oils contain the highest levels of polyphenols, antioxidants that have been linked with better health.[28]
- "Made from refined olive oils" means that the taste and composition are chemically controlled, usually to improve lower quality oils.[citation needed] In Australia, Pure, Light and Extra-Light are terms introduced by manufacturers for refined oils to avoid labeling them as such. Standards Australia's code of practice for olive oil now recognises these words as meaning refined oil. Contrary to a common consumer belief, they do not have less calories than Extra-virgin oil as implied by the names.[29]
- Cold pressed or Cold extraction means "that the oil was not heated over a certain temperature (usually 80 °F (27 °C)) during processing, thus retaining more nutrients and undergoing less degradation."[30]
- First cold pressed means "that the fruit of the olive was crushed exactly one time-i.e., the first press. The cold refers to the temperature range of the fruit at the time it is crushed."[31] In Calabria (Italy) the olives are collected in October. In regions like Tuscany or Liguria, the olives collected in November and ground often at night are too cold to be processed efficiently without heating. The paste is regularly heated above the environmental temperatures, which may be as low as 10-15 °C, to extract the oil efficiently with only physical means. Olives pressed in warm regions like Southern Italy or Northern Africa may be pressed at significantly higher temperatures although not heated. While it is important that the pressing temperatures be as low as possible (generally below 25 °C) there is no international reliable definition of "cold pressed".
Furthermore, there is no "second" press of virgin oil, so the term "first press" means only that the oil was produced in a press vs. other possible methods.
- PDO and PGI refers to olive oils with "exceptional properties and quality derived from their place of origin as well as from the way of their production".[32]
- The label may indicate that the oil was bottled or packed in a stated country. This does not necessarily mean that the oil was produced there. The origin of the oil may sometimes be marked elsewhere on the label; it may be a mixture of oils from more than one country.[24]
- The U.S. Food and Drug Administration permitted a claim on olive oil labels stating: "Limited and not conclusive scientific evidence suggests that eating about two tablespoons (23g) of olive oil daily may reduce the risk of coronary heart disease."[33]
The adulteration of oil can be no more serious than passing off inferior, but safe, product as superior olive oil, but there are no guarantees. It is believed that almost 700 people died as a consequence of consuming rapeseed oil adulterated with aniline intended for use as an industrial lubricant, but sold in 1981 as olive oil in Spain (see toxic oil syndrome).[34]
There have been allegations that regulation, particularly in Italy and Spain, is extremely lax and corrupt. Major Italian and Spanish shippers are claimed to routinely adulterate olive oil and that only about 40% of olive oil sold as "extra virgin" actually meets the specification.[35] In some cases, colza oil (Swedish turnip) with added color and flavor has been labeled and sold as olive oil.[36] This extensive fraud prompted the Italian government to mandate a new labeling law in 2007 for companies selling olive oil, under which every bottle of Italian olive oil would have to declare the farm and press on which it was produced, as well as display a precise breakdown of the oils used, for blended oils.[37] In February 2008, however, EU officials took issue with the new law, stating that under EU rules such labeling should be voluntary rather than compulsory.[38] Under EU rules, olive oil may be sold as Italian even if it only contains a small amount of Italian oil.[37]
In March 2008, 400 Italian police officers conducted "Operation Golden Oil", arresting 23 people and confiscating 85 farms after an investigation revealed a large-scale scheme to relabel oils from other Mediterranean nations as Italian.[39] In April 2008, another operation impounded seven olive oil plants and arrested 40 people in nine provinces of northern and southern Italy for adding chlorophyll to sunflower and soybean oil, and selling it as extra virgin olive oil, both in Italy and abroad; 25,000 liters of the fake oil were seized and prevented from being exported.[40]
On March 15, 2011, the Florence, Italy prosecutor's office, working in conjunction with the forestry department, indicted two managers and an officer of Carapelli, one of the brands of the Spanish company Grupo SOS (which recently changed its name to Deoleo). The charges involved falsified documents and food fraud. Carapelli lawyer Neri Pinucci said the company was not worried about the charges and that "the case is based on an irregularity in the documents."[41]
On February 2012 an alleged international olive oil scam in which palm, avocado, sunflower and other cheaper oils were passed off as olive oil were released by Spanish police. They said the oils were blended in an industrial biodiesel plant and adulterated in a way to hide markers that would have revealed their true nature. The oils were not toxic, however, and posed no health risk, according to a statement by the Guardia Civil. Nineteen people were arrested following the year-long joint probe by the police and Spanish tax authorities, part of what they call Operation Lucerna.[42]
Two diametrically opposed trends exist in the olive-oil business. In the first, toward high quality olive oil, new milling technologies such as stainless steel mills, high speed centrifuges, temperature and oxygen controlled storage tanks are making it possible to produce the best extra-virgin olive oils in history; fresh, complex and every bit as varied as wine varietals. (There are about seven hundred different kinds of olives.) Consumer demand for high-quality olive oil in all of its variety, both in Europe and in North America, is skyrocketing.
On the other hand, there's a strong downward pressure on olive-oil quality, especially among the huge Spanish owned olive-oil traders and bottling companies (which also control biggest Italian brands). There is a massive output of low grade olive oils, particularly in Spain and North Africa, which producers are selling as "extra virgin" olive oil, even though this low grade oil doesn't meet the requirements of the extra-virgin grade. (E.U. and U.S. trade standards require extra-virgin olive oil to be free of sensory defects and these oils are deeply flawed.) New methods of chemical refinement, commonly known as "deodorization," allow unscrupulous producers to remove sensory defects and sell their sub-par oils, illegally, as extra-virgin. (By law, extra-virgin olive oil cannot have undergone chemical manipulation.). In Spain refineries are capable to cope with this technology. In 2012 The spot price of "extra-virgin olive oil" in European markets has dropped as low as 1.8 euro per kilo (about a liter). Honest producers around the world are being undercut by cheap foreign oil.[43]
| Certification |
Name |
| P.G.I. |
Agios Mattheos Corfu |
| P.D.O. |
Apokoronas Chania Crete |
| P.D.O. |
Arxanes Irakliou Crete |
| P.D.O. |
Viannos Irakliou Crete |
| P.D.O. |
Vorios Mylopotamos Rethymnis Crete |
| P.D.O. |
Trizinia |
| P.D.O. |
Thrapsano |
| P.G.I. |
Zakynthos |
| P.G.I. |
Thassos |
| P.G.I. |
Kefalonia |
| P.D.O. |
Kolymvari Chania Crete |
| P.D.O. |
Kranidi Argolidas |
| P.D.O. |
Krokees Lakonias |
| P.G.I. |
Olympia |
| P.G.I. |
Chania Crete |
| P.G.I. |
Lakonia |
| P.G.I. |
Lesvos or Mytilini |
| P.D.O. |
Lygourio Asklipiiou |
| P.D.O. |
Peza Irakliou Crete |
| P.D.O. |
Petrina Lakonias |
| P.G.I. |
Preveza |
| P.D.O. |
Finiki Lakonias |
| P.G.I. |
Rodos |
| P.G.I. |
Samos |
| P.D.O. |
Kalamata |
| P.D.O. |
Sitia Lasithiou Crete |
| P.D.O. |
Selino Crete |
Greece has by far the largest per capita consumption of olive oil worldwide, over 26 liters per person per year; Spain and Italy, around 14 l; Tunisia, Portugal, Syria, Jordan and Lebanon, around 8 l. Northern Europe and North America consume far less, around 0.7 l, but the consumption of olive oil outside its home territory has been rising steadily.
The main producing and consuming countries are:
| Country |
Production in tons (2010)[45] |
Production % (2010) |
Consumption (2005)[46] |
Annual per capita consumption (kg)[47] |
| World |
3,269,249 |
100% |
100% |
0.43 |
| Spain |
1,487,000 |
45.5% |
20% |
13.62 |
| Italy |
548,500 |
16.8% |
30% |
12.35 |
| Greece |
352,800 |
10.8% |
9% |
23.7 |
| Syria |
177,400 |
5.4% |
3% |
7 |
| Morocco |
169,900 |
5.2% |
2% |
11.1 |
| Turkey |
161,600 |
4.9% |
2% |
1.2 |
| Tunisia |
160,100 |
4.9% |
2% |
5 |
| Portugal |
66,600 |
2.0% |
2% |
1.8 |
| Algeria |
33,600 |
1.0% |
2% |
7.1 |
| Others |
111,749 |
3.3% |
18% |
1.18 |
A cold press olive oil machine in
Israel.
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 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).
- 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 technically meaningless, as there is no "second" press.
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).[48]
Olive oil is composed mainly of the mixed triglyceride esters of oleic acid and palmitic acid and of other fatty acids, along with traces of squalene (up to 0.7%) and sterols (about 0.2% phytosterol and tocosterols). The composition varies by cultivar, region, altitude, time of harvest, and extraction process.
Olive oil contains a group of related natural products, called natural phenols, with potent antioxidant properties that give extra-virgin unprocessed olive oil its bitter and pungent taste and are esters of tyrosol and hydroxytyrosol, including oleocanthal and oleuropein.[49] Olive oil is a source of at least 30 phenolic compounds.[50]
Other phenolic constituents include aldehydic secoiridoids, flavonoids and lignans (acetoxypinoresinol, pinoresinol).[51] The latter two compounds are only present in extra virgin oil.[52]
As they are the least processed forms of olive oil, extra virgin or virgin olive oil have more monounsaturated fatty acids than other olive oil. These types also contain more polyphenols, which may have benefits for the heart.[53]
1tbsp of olive oil (13.5g) contains the following nutritional information according to the USDA:[54]
- Calories : 119
- Fat: 13.50
- Carbohydrates: 0
- Fibers: 0
- Protein: 0
Evidence from epidemiological studies also suggests that a higher proportion of monounsaturated fats in the diet is linked with a reduction in the risk of coronary heart disease.[55] This is significant because olive oil is considerably rich in monounsaturated fats, most notably oleic acid.
In the United States, producers of olive oil may place the following health claim on product labels:
- Limited and not conclusive scientific evidence suggests that eating about 2 tbsp. (23 g) of olive oil daily may reduce the risk of coronary heart disease due to the monounsaturated fat in olive oil. To achieve this possible benefit, olive oil is to replace a similar amount of saturated fat and not increase the total number of calories you eat in a day.[56]
This decision was announced November 1, 2004, by the Food and Drug Administration after application was made to the FDA by producers. Similar labels are permitted for foods rich in omega-3 fatty acids such as walnuts and hemp seed.[57]
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.[58] Additionally, olive oil protects against heart disease as it controls the "bad" levels of LDL cholesterol and raises levels of the "good" cholesterol, HDL.[33]
Another health benefit of olive oil seems to be its property to displace omega-6 fatty acids, while not having any impact on omega-3 fatty acids. This way, olive oil helps to build a more healthy balance between omega-6 fats and omega-3 fats.[59]
Unlike saturated fats, olive oil lowers total cholesterol and LDL levels in the blood.[60] It is also known to lower blood sugar levels and blood pressure.[61]
Olive oil contains the monounsaturated fatty acid oleic acid, antioxidants such as vitamin E and carotenoids, and oleuropein, a chemical that may help prevent the oxidation of LDL particles.[62]
Olive oil contains a wide variety of valuable antioxidants that are not found in other oils. Hydroxytyrosol is thought to be the main antioxidant compound in olives, and believed to play a significant role in the many health benefits attributed to olive oil. Epidemiological studies suggest that olive oil has a protective effect against certain malignant tumours in the breast, prostate, endometrium and digestive tract. Research has revealed that the type rather than the quantity of fat seems to have more implications for cancer incidence.[63]
Hydroxytyrosol (2-(3,4-Di-hydroxyphenyl)-ethanol or DHPE) is a phenolic component of extra-virgin olive oil. An olive oil fraction containing DHPE can inhibit platelet aggregation and eicosanoid (thromboxane B2) formation in vitro.[64]
Oleocanthal from olive oil is a non-selective inhibitor of cyclooxygenase (COX) similar to classical NSAIDs like ibuprofen. It has been suggested that long-term consumption of small quantities of this compound from olive oil may be responsible in part for the low incidence of heart disease associated with a Mediterranean diet.
In addition to the internal health benefits of olive oil, topical application is quite popular with fans of natural health remedies. Extra virgin olive oil is the preferred grade for moisturizing the skin, especially when used in the oil cleansing method (OCM). OCM is a method of cleansing and moisturizing the face with a mixture of extra virgin olive oil, castor oil (or another suitable carrier oil) and a select blend of essential oils.[citation needed] Olive oil has been known for generations not only for its healing qualities but also as a natural, deep penetration moisturizer, regenerating skin cells and softening the tissue.[65] Olive oil is also used by some to reduce ear wax buildup.[66]
Olive oil can be used as an effective shaving oil to shave facial and other body hair.[67][68]
Studies on mice showed that application of olive oil immediately following exposure to UVB rays has a preventive effect on the formation of tumors and skin cancer.[69][70]
It is also widely used in cosmetics and soaps, and are immensely beneficial in adding smoothness and softness to dry scaly skin, especially during the winter.[71]
Olive oil is unlikely to cause allergic reactions, and as such is used in preparations for lipophilic drug ingredients. It does have demulcent properties, and mild laxative properties, acting as a stool softener. It is also used at room temperature as an ear wax softener. Olive oil is also a potent blocker of intestinal contractions, and can be used to treat excessive Borborygmus.
Preliminary research indicates that olive oil could possibly be a chemopreventive agent for peptic ulcer or gastric cancer, but confirmation requires further in vivo study.[72] Olive oil was also found to reduce oxidative damage to DNA and RNA, which may be a factor in preventing cancer.[73]
Unsaturated oils, such as olive oil, have a short shelf life and are prone to becoming rancid from oxidation, which will produce toxic byproducts and a bitter taste.[74] Protection of unsaturated oils from heat and light will delay spoilage.
Olive oil is the main cooking oil in countries surrounding the Mediterranean Sea.
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 more one should prefer the use of refined olive oils. When extra virgin olive oil is heated above 350 °F (177 °C), 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.[citation needed]
Choosing a cold-pressed olive oil can be similar to selecting a wine. The flavour of these oils varies considerably and a particular oil may be more suited for a particular dish. Also, people who like lots of tannins in their red wines might prefer more bitter olive oils.
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 surely 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 from and by the moment when the olives are harvested and ground (less ripe olives give more bitter and spicy flavors, which is a positive attribute - riper olives give a sweeter sensation in the oil).
Olive oil has more uses than as food; it also works as a natural and safe lubricant, such as lubricating the machinery that is used within the kitchen (grinders, blenders, cookware, etc.)
Olive oil also has religious symbolism for healing and strength and to consecration—God's setting a person or place apart for special work. This may be related to its ancient use as a medicinal agent and for cleansing athletes by slathering them in oil then scraping them.
In Jewish observance, olive oil is the only fuel allowed to be used in the seven-branched Menorah in the Mishkan service during the Exodus of the tribes of Israel from Egypt, and later in the permanent Temple in Jerusalem. It was obtained by using only the first drop from a squeezed olive and was consecrated for use only in the Temple by the priests, which is where the expression pure olive oil originates, stored in special containers. A menorah similar to the Menorah used in the Mishkan is now used during the holiday of Hanukkah that celebrates the miracle of the last of such containers being found during the re-dedication of the Temple (163 BC), when its contents lasted for far longer than they were expected to, allowing more time for more oil to be made. Although candles can be used to light the hanukkiah, oil containers are preferred, to imitate the original Menorah. Another use of oil in Jewish religion is for anointing the kings of the Kingdom of Israel, originating from King David. Tzidkiyahu was the last anointed King of Israel. One unusual use of olive oil in the Talmud is for bad breath, by creating a water-oil-salt mouthwash.[citation needed] The Talmud also states that frequent consumption of olive oil is good for one's memory.[81]
The Catholic and Orthodox Churches use olive oil for the Oil of Catechumens (used to bless and strengthen those preparing for Baptism) and Oil of the Sick (used to confer the Sacrament of Anointing of the Sick or Unction). Olive oil mixed with a perfuming agent such as balsam is consecrated by bishops as Sacred Chrism, which is used to confer the sacrament of Confirmation (as a symbol of the strengthening of the Holy Spirit), in the rites of Baptism and the ordination of priests and bishops, in the consecration of altars and churches, and, traditionally, in the anointing of monarchs at their coronation. The Church of Jesus Christ of Latter-day Saints (Mormons) and a number of other religions use olive oil when they need to consecrate an oil for anointings.
Eastern Orthodox Christians still use oil lamps in their churches, home prayer corners and in the cemeteries. A vigil lamp consists of a votive glass containing a half-inch of water and filled the rest with olive oil. The glass has a metal holder that hangs from a bracket on the wall or sits on a table. A cork float with a lit wick floats on the oil. To douse the flame, the float is carefully pressed down into the oil. Makeshift oil lamps can easily be made by soaking a ball of cotton in olive oil and forming it into a peak. The peak is lit and then burns until all the oil is consumed, whereupon the rest of the cotton burns out. Olive oil is a usual offering to churches and cemeteries.
In the Orthodox Church, olive oil is a product not consumed during lent or penance while Orthodox monks use it sparingly in their diet. Exceptions are in feast days and Sundays.
In Islam, olive oil is mentioned in the Quranic verse: "God is the light of the Heavens and the Earth. An example of His light is like a lantern inside which there is a torch, the torch is in a glass bulb, the glass bulb is like a bright planet lit by a blessed olive tree, neither Eastern nor Western, its oil almost glows, even without fire touching it, light upon light." The Qur'an also mentions olives as a plant of significance: "By the fig and the olive, and the Mount Sinai, and this secure city."[82] Olive oil is also reported to have been recommended by Muhammad in the following terms: "Consume olive oil and anoint it upon your bodies since it is of the blessed tree."
Olive oil is also used in soap making and as lamp oil. It also makes an excellent lubricant, and can be used in place of machine oil.[citation needed]
Olive oil has also been used as both solvent and ligand in the synthesis of cadmium selenide quantum dots.[83]
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