Olive oil

2008/9 Schools Wikipedia Selection. Related subjects: Food

Olive oil
Olive oil bottle.
Fat composition
Saturated fats	Palmitic acid: 7.5–20.0 % Stearic acid: 0.5–5.0 % Arachidic acid: <0.8% Behenic acid: <0.3% Myristic acid: <0.1% Lignoceric acid: <1.0%
Unsaturated fats	yes
Monounsaturated fats	Oleic acid: 55.0–83.0% Palmitoleic acid: 0.3–3.5%
Polyunsaturated fats	Linoleic acid: 3.5–21.0 % Linolenic acid: <1.5%
Properties
Food energy per 100g	3700 kJ (890 kcal)
Melting point	−6.0 °C (21 °F)
Boiling point	300 °C (570 °F)
Smoke point	190 °C (375 °F) (virgin) 210 °C (410 °F) (refined)
Specific gravity at 20 °C	0.9150–0.9180 (@ 15.5 °C)
Viscosity at 20 °C	84 cP
Refractive index	1.4677–1.4705 (virgin and refined) 1.4680–1.4707 (pomace)
Iodine value	75–94 (virgin and refined) 75–92 (pomace)
Acid value	maximum: 6.6 (refined and pomace) 0.6 (extra-virgin)
Saponification value	184–196 (virgin and refined) 182–193 (pomace)
Peroxide value	20 (virgin) 10 (refined and pomace)

Olive oil is a fruit oil obtained from the olive (Olea europaea; family Oleaceae along with lilacs, jasmine and ash trees), a traditional tree crop of the Mediterranean Basin. The wild olive tree originated in Asia Minor, today the nation of Turkey. It is commonly used in cooking, cosmetics, pharmaceuticals, and soaps and as a fuel for traditional oil lamps.

Market

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 Middle East.

World production in 2002 was 2.6 million metric tons, of which Spain contributed 40% to 45%. In 2006 Turkey accounted for about 5% of world production, similar to the Spanish province of Jaen alone, well known for the biggest olive groves in the world..

Of the European production, 93% comes from Spain, Italy, Greece, and Turkey (in order of annual production).

Greece devotes 60% of its cultivated land to olive growing. It is the world's top producer of black olives and has more varieties of olives than any other country. Greece holds third place in world olive production with more than 132 million trees, which produce approximately 350,000 tons of olive oil annually, of which 82% is extra-virgin (see below for an explanation of terms). About half of the annual Greek olive oil production is exported, but only some 5% of this reflects the origin of the bottled product. Greece exports mainly to European Union (EU) countries, principally Italy, which receives about three-quarters of total exports. Olives are grown for oil in mainland Greece, with Peloponnese being the source of 65% of Greek production, as well as in Crete, the Aegean Islands and Ionian Islands.

Among the many different olive varieties or cultivars in Italy are Frantoio, Leccino Pendolino, and Moraiolo. In Spain the most important varieties are the Picual, Alberquina, Hojiblanca, and Manzanillo de Jaén. In Greece : Koroneiki. In France : Picholine. In California : Mission. In Portugal : Galega. The oil from the varieties varies in flavour and stability (shelf life).

In North America, Italian and Spanish olive oils are the best-known, and top-quality extra-virgin oils from Italy, Spain and Greece are sold at high prices, often in "prestige" packaging. A large part of US olive oil imports come from the EU, especially Spain. The US imported 28.95 million gallons of olive oil in 1994, a 215% increase from 1984. The US is Italy's biggest customer, importing 22% of total Italian production of 131.6 million gallons in 1994.

Regulation and adulteration

The International Olive Oil Council (IOOC) is an intergovernmental organization based in Madrid, Spain, with 23 member states. 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 IOOC member nations. The United States is not a member of the IOOC, and the US 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 IOOC existed. The California Olive Oil Council, a private trade group, is petitioning the USDA to adopt IOOC rules.

The IOOC officially governs 95% of international production and holds great influence over the rest. IOOC terminology is precise, but it can lead to confusion between the words that describe production and the words used on retail labels. Olive oil is classified by how it was produced, by its chemistry, and by its flavor. All production begins by transforming the olive fruit into olive paste. This paste is then malaxed 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 EU regulates the use of different protected designation of origin labels for olive oils.

An article by Tom Mueller in the August 13, 2007 Issue of the The New Yorker alleges that regulation, particularly in Italy, is extremely lax and corrupt. Mueller states that major Italian shippers routinely adulterate olive oil and that only about 40% of olive oil sold as "extra virgin" actually meets the specification. In some cases, colza oil with added colour and flavor has been labeled and sold as olive oil. 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. 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. Under EU rules, olive oil may be sold as Italian even if it only contains a small amount of Italian oil.

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. 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.

Adulterated oil is usually no more serious than passing off inferior, but safe, product as superior olive oil, but there are no guarantees. Almost 700 people died, it is believed, as a consequence of consuming rapeseed (canola) oil adulterated with aniline intended for use as an industrial lubricant, but sold in 1981 as olive oil in Spain .

Industrial grades

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; the retail labels extra-virgin olive oil and virgin olive oil cannot contain any refined oil.
• Pomace olive oil means oil extracted from the pomace using chemical 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.

In order 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 IOOC member nations

In countries which adhere to the standards of the IOOC the labels in stores show an oil's grade. The US is not a member.

• Extra-virgin olive oil comes from cold pressing of the olives, contains no more than 0.8% acidity, and is judged to have a superior taste. Extra-virgin and virgin olive oil may not contain refined oil.
• Virgin olive oil has an acidity less than 2%, 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 or extra-virgin oil.
• Olive oil is a blend of virgin oil and refined oil, of no more than 1.5% acidity. It commonly lacks a strong flavor.
• Olive-pomace oil is a blend of refined pomace olive oil and possibly some virgin oil. It is fit for consumption, but may not be described simply as olive oil. Olive-pomace oil is rarely sold at retail; it is often used for certain kinds of cooking in restaurants.
• 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.

Label wording

Olive oil vendors choose the wording on their labels very carefully.

• "100% Pure Olive Oil" is often the lowest quality available in a retail store: better grades would have "virgin" on the label.
• "Made from refined olive oils" means that the taste and acidity were chemically controlled.
• "Light olive oil" means refined olive oil, with less flavour. All olive oil has 120 calories per tablespoon (34 J/ml).
• "From hand-picked olives" implies that the oil is of better quality, since producers harvesting olives by mechanical methods are inclined to leave olives to over-ripen in order to increase yield.
• "First cold press" means that the oil in bottles with this label is the first oil that came from the first press of the olives. The word cold is important because if heat is used, the olive oil's chemistry is changed. It should be noted that extra-virgin olive oil is cold pressed, but not necessarily the first oils.
• 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 several places.

Retail grades in the United States

As the United States is not a member, the IOOC retail grades have no legal meaning there; terms such as "extra virgin" may be used without legal restrictions. The U.S. Department of Agriculture (USDA), which controls this aspect of labeling, currently lists four grades of olive oil: "Fancy", "Choice", "Standard", and "Substandard", also called Grades A through D. These grades were established in 1948, and are based on acidity, absence of defects, odour and flavor.

Global consumption

Greece has by far the largest per capita consumption of olive oil worldwide, over 26 liters per year; Spain and Italy, around 14 L; Tunisia, Portugal and Syria, 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.

Price is an important factor on olive oil consumption in the world commodity market. In 1997, global production rose by 47%, which replenished low stocks, lowered prices, and increased consumption by 27%. Overall, world consumption trends are up by 2.5%. Production trends are also up due to expanded plantings of olives in Europe, Latin America, the USA, and Australia.

Olive tree in Portugal

Global market

The main producing and consuming countries are:

Extraction

The most traditional way of making olive oil is by grinding olives. Green olives produce bitter oil, and overripe olives produce rancid oil, so care is taken to make sure the olives are perfectly ripened. First the olives are ground into paste using large millstones. The olive paste generally stays under the stones for 30–40 minutes. The oil collected during this part of the process is called virgin oil. After grinding, the olive paste is spread on fibre disks, which are stacked on top of each other, then placed into the press. Pressure is then applied onto the disk to further separate the oil from the paste. This second step produces a lower grade of oil.

Constituents

Olive oil is composed mainly of oleic acid and palmitic acid and 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 with potent antioxidant properties which give extra-virgin unprocessed olive oil its bitter and pungent taste and which are esters of tyrosol and hydroxytyrosol, including oleocanthal and oleuropein.

Human health

Evidence from epidemiological studies suggests that a higher proportion of monounsaturated fats in the diet is linked with a reduction in the risk of coronary heart disease. 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 two tablespoons (23 grams) 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.

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.

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.

But some clinical evidence suggests that it is olive oil's phenolic content, rather than its fatty acid profile, that is responsible for at least some of its cardioprotective benefits. For example, a clinical trial published in 2005 compared the effects of different types of olive oil on arterial elasticity. Test subjects were given a serving of 60 grams of white bread and 40 milliliters of olive oil each morning for two consecutive days. The study was conducted in two stages. During the first stage, the subjects received polyphenol-rich oil (extra virgin oil contains the highest amount of polyphenol antioxidants). During the second phase, they received oil with only one fifth the phenolic content. The elasticity of the arterial walls of each subject was measured using a pressure sleeve and a Doppler laser. It was discovered that after the subjects had consumed olive oil high in polyphenol antioxidants, they exhibited increased arterial elasticity, while after the consumption of olive oil containing fewer polyphenols, they displayed no significant change in arterial elasticity. It is theorized that, in the long term, increased elasticity of arterial walls reduces vascular stress and consequentially the risk of two common causes of death—heart attacks and stroke. This could, at least in part, explain the lower incidence of both diseases in regions where olive oil and olives are consumed on a daily basis.

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.

Jeanne Calment, who holds the record for the longest confirmed lifespan, reportedly attributed her longevity and relatively youthful appearance to olive oil, which she said she poured on all her food and rubbed into her skin.

However, some of these benefits are disputed. Several scientific studies doubt some of the previously stated positive effects and state several negative effects of olive oil such as impairment of the dilation of the arteries.

Culinary use

Ultra-virgin olive oil is often used for dressing salads and foods to be eaten cold. It is used for frying ingredients (e.g., onions) which are used in stews and similar dishes. It can be used for deep frying. Olive oil, particularly the unrefined grades, gives a pronounced flavour to foods, and is used either where the flavour is desired, or in countries where olive oil is the most common cooking oil.

The flavour of cold-pressed olive oils vary considerably, and choosing an oil can be similar to selecting a wine. It is not simply a matter of better and worse oils; individual tastes differ, and different oils may be more suited for different dishes.

A factor which is not realised in countries which do not produce oil is that the freshness makes a big difference; a very fresh oil, as available in an oil-producing region, is noticeably different from the older oils available elsewhere. And oils deteriorate as they become stale.

Medicinal use

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.

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.

History

Ancient Greek olive oil production workshop in what is now Kilizman,Turkey

The Manufacture of Oil, drawn and engraved by J. Amman in the Sixteenth Century.

Homer called it "liquid gold." In ancient Greece, athletes ritually rubbed it all over their body. 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.

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", 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.

The olive tree is native to the Mediterranean basin; wild olives were collected by Neolithic peoples as early as the 8th millennium BC. The wild olive tree has possibly originated in Asia Minor..

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 ; 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. 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.

Ancient oil press
Bodrum Museum of Underwater Archaeology, Bodrum, Turkey

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.

Many ancient presses still exist in the Eastern Mediterranean region, and some dating to the Roman period are still in use today.

Eastern Mediterranean

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.

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.

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.

Until 1500 BC, the 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. 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.. 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 the Kingdom of Israel c. 1000 BC. 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 legend, 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.

Religious use

In Jewish observance, olive oil is the only fuel allowed to be used in the seven-branched Menorah (not a candelabrum since the use of candles was not allowed) 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 copy of the Menorah 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 then 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.

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. 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). Olive oil mixed with a perfuming agent like 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 and home prayer corners. 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 lit a wick floats on the oil. To douse the flame, the float is carefully pressed down into the oil.

In Islam, olive oil is mentioned in the Quranic verse: "God is the light of heavens and earth. An example of His light is like a lantern inside which there is a tourch, the tourch 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 sacred plant: "By the fig and the olive, and the Mount of Sinai, and this secure city." Olive oil is also reported to have been recommended by the Muslim Prophet Muhammad in the following terms: "Consume olive oil and anoint it upon your bodies since it is of the blessed tree." He also stated that it cures 70 diseases.