Olive

Olive
Olea europaea, Dead Sea, Jordan
Scientific classification
Kingdom: Plantae Division: Magnoliophyta Class: Magnoliopsida Order: Lamiales Family: Oleaceae Genus: Olea Species: O. europaea
Binomial name
Olea europaea L.

19th century illustration

Olive is the common name for a evergreen tree or shrub, Olea europaea, in the flowering plant family Oleaceae, characterized by small size, squat shape, oblong opposite leaves, white flowers, and ovoid fruit. The name olive also refers to the edible fruit of this tree, a small drupe that is major agricultural importance in the Mediterranean region as the source of olive oil and as a food. It has been cultivated for thousands of years in the Mediterranean region, which remains the chief area of olive production, but the tree has been introduced to other subtropical and warm temperate climates. Olive is also the common name for the entire Oleaceae family, which includes the lilac, jasmine, forsythia, and ash.

Olive oil is commonly used in cooking, cosmetics, pharmaceuticals, and soaps and as a fuel for traditional oil lamps. Olive oil is considered a healthy oil because of its high content of monounsaturated fat (mainly oleic acid) and polyphenols.

Description

Oleaceae, the olives and relatives, is a plant family containing 24 extant genera of woody plants, including shrubs, trees and vines. They are characterized by opposite leaves that may be simple or pinnately-compound. The calyx and corolla are four-lobed.

Many members of the family are economically significant. The olive proper, Olea europaea, is extremely important for its fruit and the oil extracted from it. The ashes, genus Fraxinus, are valued for their tough wood, and forsythia, lilacs, jasmines, privets, and fringetrees are all valued as ornamental plants.

The olive, Olea europaea, is native to coastal areas of the eastern Mediterranean region, from Syria and the maritime parts of Asia Minor to northern Iran at the south end of the Caspian Sea. It is short and squat, and rarely exceeds 8-15 meters in height.

The silvery green leaves are oblong in shape, measuring 4-10 centimeters (cm) long and 1-3 cm wide. The trunk is typically gnarled and twisted.

The small white flowers, with four-cleft calyx and corolla, two stamens and bifid stigma, are borne generally on the last year's wood, in racemes springing from the axils of the leaves.

The fruit is a small drupe 1-2.5 cm long, thinner-fleshed and smaller in wild plants than in orchard cultivars. Olives are harvested at the green stage or left to ripen to a rich purple color (black olive). Canned black olives may contain chemicals that turn them black artificially.

History

The olive is one of the plants most cited in recorded literature. In Homer's Odyssey, Odysseus crawls beneath two shoots of olive that grow from a single stock. The Roman poet Horace mentions it in reference to his own diet, which he describes as very simple: "As for me, olives, endives, and smooth mallows provide sustenance" (Horace 30 B.C.E.). Lord Monboddo comments on the olive in 1779 as one of the foods preferred by the ancients and as one of the most perfect foods (Knight 1993).

It is not known exactly when the wild olive became a domesticated crop. A leaf from an olive tree is mentioned in chapter 8 of Genesis when Noah finds one in the dove's beak. In the Homeric world, as depicted in the Iliad, olive oil is known only as a luxury of the wealthy—an exotic product, prized chiefly for its value in grooming. Warriors would anoint themselves after bathing, and the body of Patroclus is described as being oiled in this way. But no mention of the cultivation of the plant is made, whereas a vineyard is mentioned in the description of Achilles' shield. But, although no reference to the cultivation of the olive occurs in the Iliad, the presence of the tree in the garden of Alcinous and other allusions show it to have been known when the Odyssey was written.

Some of the different varieties of marinated olives (black and green) sold by farmers and in shops

It is not known where the olive tree was first cultivated, but it traces every early to Asia Minor and spread to the Mediterranean. Tradition points to the limestone hills of Attica as the seat of its first cultivation on the Hellenic peninsula. The tree features in the myths of the founding of Athens: An olive is said to have sprung from the barren rock at the bidding of Athena, the city state's patron, when she fought with Poseidon. This suggests some relation to the first planting of the olive in Greece. There is also the remarkable story told by Herodotus of the Epidaurians, who, when their crops failed, were told by the Delphic Sibyl oracle to erect statues to Damia and Auxesia (symbols of fertility) carved from the wood of the true garden olive, then possessed only by the Athenians. They did so when granted their request for a tree by the Athenians (on the condition of making an annual sacrifice to Athena) and their lands became fertile again. The sacred tree of the goddess long stood on the Acropolis, and, though destroyed in the Persian invasion, sprouted again from the root. Some suckers of the original tree were said to have produced the later revered olive trees of the Academy.

By the time of the Athenian statesman Solon (c. 638 B.C.E.–558 B.C.E.), the olive had spread so much that he found it necessary to enact laws to regulate the cultivation of the tree in Attica. From here it gradually spread to all the Athenian allies and tributary states. Phoenician vessels may have taken olive cuttings to the Ionian coast, where it abounded in the time of Thales; the olives of the Sporades, Rhodes and Crete perhaps had a similar origin. Samos, if we may judge from the epithet of Aeschylus, must have had the plant long before the Persian Wars.

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. The leafy branches of the olive tree, as a symbol of abundance, glory, and peace, were used to crown the victors of friendly games and bloody war, and the oil of its fruit has anointed the noblest of heads throughout history. As emblems of benediction and purification, they were also ritually offered to deities and powerful figures: Some were even found in Tutankhamen's tomb.

Homer called it "liquid gold." In ancient Greece, athletes ritually rubbed it all over their body. Drops of it seeped into the bones of dead saints and martyrs through holes in their tombs.

Old trees

Pliny the Elder told of a sacred Greek olive tree that was 1600 years old. Several trees in the Garden of Gethsemane (from the Hebrew words "gat shemanim" or oil press) in Jerusalem are claimed to date back to the time of Jesus. Some Italian olive trees are believed to date back to Roman times, although identifying progenitor trees in ancient sources is difficult.

However, the age of an olive tree in Crete, claimed to be over 2,000 years old, has been determined on the basis of tree ring analysis. Another, on the island of Brijuni (Brioni), Istria in Croatia, a well-known olive tree has been calculated to be about 1,600 years old. It still gives fruit (about 30 kg per year), which is made into top quality olive oil. The olive tree is one of the symbols of Athena, the Greek goddess, and is frequently mentioned in the Bible and the Qur'an.

Cultivation and uses

An example of black olives.

The olive has been cultivated since ancient times as a source of olive oil, fine wood, and olives for consumption. The fruit, naturally bitter, typically subjected to fermentation or cured with lye or brine to make it more palatable.

Green olives and black olives are soaked in a solution of sodium hydroxide and washed thoroughly in water to remove oleuropein, a naturally bitter carbohydrate.

Green olives are allowed to ferment before being packed in a brine solution. American black ("California") olives are not fermented, which is why they taste milder than green olives.

It is not known when olives were first cultivated for harvest. Among the earliest evidence for the domestication of olives comes from the Chalcolithic Period archaeological site of Teleilat Ghassul in what is today modern Jordan.

The plant and its products are frequently referred to in the Bible, the Qur'an and by the earliest recorded poets. Farmers in ancient times believed olive trees would not grow well if planted more than a short distance from the sea; Theophrastus gives 300 stadia (55.6 km) as the limit. Modern experience does not always confirm this, and, though showing a preference for the coast, it has long been grown further inland in some areas with suitable climates, particularly in the southwestern Mediterranean (Iberia, northwest Africa) where winters are milder.

Olive plantation in Andalucia, Spain.

Olives are now cultivated in many regions of the world such as South Africa, Australia, New Zealand, Mediterranean Basin and California. Considerable research has been accumulated supporting the health benefits of consuming olives and olive oil (see external links below for research results).

with Mediterranean climate, such as South Africa, Chile, Australia, New Zealand, Mediterranean Basin, Palestine and California.

The olive tree provides leaves, fruit and oil. Olive leaves are used in medicinal teas.

From Olive fruit article Cultivation of the olive was (and remains) a key characteristic of Mediterranean mixed farming, and played a large part in the economic development of ancient Greece because of the suitability of olive oil as an export crop. For instance Attica, the region of Athens, was a grain importer and olive oil exporter from early historic times. The Athenian pottery industry was stimulated largely by the demand for containers in which to export olive oil.

In modern times the olive has been spread widely around the world; and, though the Mediterranean lands that were its ancient home remain the main source of the oil, the tree is now cultivated successfully in many regions unknown to its early distributors. Protected by high brick walls, a fruiting olive tree is in the Chelsea Physic Garden, London. Soon after the discovery of the Americas it was taken there by the Spanish settlers. In Chile it flourishes as luxuriantly as in its native land, the trunk sometimes attaining a large girth, while oil of fair quality is yielded by the fruit. To Peru it was carried at a later date, but has not flourished as successfully there. It was introduced into Mexico by the Jesuit missionaries of the 17th century, and to Upper California (where it stagnated later). Olive cultivation has also been attempted in the south-eastern states, especially in South Carolina, Florida and Mississippi. In the eastern hemisphere the olive has been established in many inland districts which would have been anciently considered ill-adapted for it. It was known at a comparatively early period of history in Armenia and Persia, and many olive-groves now exist in Upper Egypt. The tree has been introduced into Chinese agriculture, and has become an important addition to Australia's farmers, and there are probably few coast districts there where the tree would not flourish. In Queensland the olive has found a climate specially suitable; and in South Australia, near Adelaide. It has likewise been successfully introduced into some parts of South Africa and New Zealand.

File:Packaged olives.jpg

Packaged olives, sold as an Italian snack food

A pleasing substitute for the butter and animal fats consumed by people to the north, the olive, among the southern nations of antiquity, became an emblem not only of peace but of national wealth and domestic plenty; the branches borne in the Panathenaea, the wild olive spray of the Olympic victor, the olive crown of the Roman conqueror at ovation, and those of the equites at their imperial review were symbols of peace that, in a barbarous age, could be secured by victory alone. Among the Greeks the oil was valued as an important article of diet, as well as for its external use. The Roman people employed it widely in food and cookery—the wealthy as an indispensable adjunct to grooming; and in the luxurious days of the later empire it was said that long and pleasant life depended on two fluids: wine within and oil without. Pliny describes fifteen varieties of olive cultivated in his day, the Licinian being most esteemed, and the oil obtained from Venafrum in Campania, the finest known to Roman connoisseurs. The produce of Istria and Baetica was then regarded as second only to that of the Italian peninsula.

Gourmets from the Roman empire to the present day have valued the unripe fruit, steeped in brine, as challenging to the palate. Pickled olives, retaining their characteristic flavor, have been found among the buried stores of Pompeii. Note also that the green olive and black olive are from the same plant; green olives are pickled before being ripened, black olives after.

The bitter juice deposited during pressing of the oil (called amurca), and the astringent leaves of the tree have many virtues attributed to them by ancient authors. The oil of the bitter wild olive was employed by Roman physicians in medicine, but does not appear ever to have had a culinary use.

Subspecies

There are at least five natural subspecies distributed over a wide range:

• Olea europaea subsp. europaea (Europe)
• Olea europaea subsp. cuspidata (Iran to China)
• Olea europaea subsp. guanchica (Canaries)
• Olea europaea subsp. maroccana (Morocco)
• Olea europaea subsp. laperrinei (Algeria, Sudan, Niger)

Cultivars

Small Olive Tree

Large Olive Tree

Olive Tree Leaves

Olive Tree Trunk

Olive Flowers

A young olive plant, germinated from a seed

Monumental tree in Apulia Region - Southern Italy

There are thousands of cultivars of the olive. In Italy alone at least three hundred cultivars have been enumerated, but only a few are grown to a large extent. The main Italian cultivars are 'Leccino', 'Frantoio' and 'Carolea'. None of these can be safely identified with ancient descriptions, though it is not unlikely that some of the narrow-leaved cultivars most esteemed may be descendants of the Licinian olive. The Iberian olives are usually cured and eaten, often after being pitted, stuffed (with pickled pimento, onion, or other garnishes) and jarred in fresh brine.

Since many cultivars are self sterile or nearly so, they are generally planted in pairs with a single primary cultivar and a secondary cultivar selected for its ability to fertilize the primary one, for example, 'Frantoio' and 'Leccino'. In recent times, efforts have been directed at producing hybrid cultivars with qualities such as resistance to disease, quick growth and larger or more consistent crops.

Some particularly important cultivars of olive include:

• 'Frantoio' and 'Leccino'. These cultivars are the principal participants in Italian olive oils from Tuscany. Leccino has a mild sweet flavor while Frantoio is fruity with a stronger aftertaste. Due to their highly valued flavor, these cultivars have been migrated and are now grown in other countries.
• 'Arbequina' is a small, brown olive grown in Catalonia, Spain. As well as being used as a table olive, its oil is highly valued.
• 'Empeltre' is a medium sized, black olive grown in Spain. They are used both as a table olive and to produce a high quality olive oil.
• 'Kalamata' is a large, black olive, named after the city of Kalamata, Greece, used as a table olive. These olives are of a smooth and meatlike taste.
• 'Koroneiki' originates from the southern Peloponese, around Kalamata and Mani in Greece. This small olive, though difficult to cultivate, has a high oil yield and produces olive oil of exceptional quality.
• 'Pecholine' or 'picholine' originated in the south of France. It is green, medium size, and elongated. Their flavor is mild and nutty.
• 'Lucques' originated in the south of France (Aude département). They are green, of a large size, and elongated. The stone has an arcuated shape. Their flavor is mild and nutty.
• 'Souri' (Syrian) originated in Lebanon and is widespread in the Levant. It has a high oil yield and exceptionally aromatic flavor.
• 'Nabali' is a Palestinian cultivar also known locally as 'Baladi', which along with 'Souri' and 'Malissi' are considered to produce among the highest quality olive oil in the world.
• 'Barnea' is a modern cultivar bred in Israel to be disease resistant and to produce a generous crop. It is used both for oil and for table olives. The oil has a strong flavor with a hint of green leaf. Barnea is widely grown in Israel and in the southern hemisphere, particularly in Australia and New Zealand.
• 'Maalot' is another modern, disease-resistant, Eastern Mediterranean cultivar derived from the North African 'Chemlali' cultivar. The olive is medium sized, round, has a fruity flavor and is used almost exclusively for oil production.
• 'Mission' originated on the California Missions and is now grown throughout the state. They are black and generally used for table consumption.

Growth and propagation

Olive trees show a marked preference for calcareous soils, flourishing best on limestone slopes and crags, and coastal climate conditions. They tolerate drought well, thanks to their sturdy and extensive root system. Olive trees can be exceptionally long-lived, up to several centuries, and can remain productive for as long, provided they are pruned correctly and regularly.

The olive tree grows very slowly, but over many years the trunk can attain a considerable diameter. A. P. de Candolle recorded one exceeding 10 m in girth. They can possibly reach great age and the trees rarely exceed 15 m in height, and are generally confined to much more limited dimensions by frequent pruning. The yellow or light greenish-brown wood is often finely veined with a darker tint; being very hard and close-grained, it is valued by woodworkers.

The olive is propagated in various ways, but cuttings or layers are generally preferred; the tree roots easily in favorable soil and throws up suckers from the stump when cut down. However, yields from trees grown from suckers or seeds are poor; it must be budded or grafted onto other specimens to do well (Lewington and Parker, 114). Branches of various thickness are cut into lengths of about 1 m and, planted deeply in manured ground, soon vegetate; shorter pieces are sometimes laid horizontally in shallow trenches, when, covered with a few centimeters of soil, they rapidly throw up sucker-like shoots. In Greece, grafting the cultivated tree on the wild form is a common practice. In Italy, embryonic buds, which form small swellings on the stems, are carefully excised and planted beneath the surface, where they grow readily, their buds soon forming a vigorous shoot.

Occasionally the larger boughs are marched, and young trees thus soon obtained. The olive is also sometimes raised from seed, the oily pericarp being first softened by slight rotting, or soaking in hot water or in an alkaline solution, to facilitate germination.

Where the olive is carefully cultivated, as in Languedoc and Provence, the trees are regularly pruned. The pruning preserves the flower-bearing shoots of the preceding year, while keeping the tree low enough to allow the easy gathering of the fruit. The spaces between the trees are regularly fertilized. The crop from old trees is sometimes enormous, but they seldom bear well two years in succession, and in many instances a large harvest can only be reckoned upon every sixth or seventh season.

A calcareous soil, however dry or poor, seems best adapted to its healthy development, though the tree will grow in any light soil, and even on clay if well drained; but, as remarked by Pliny, the plant is more liable to disease on rich soils, and the oil is inferior to the produce of the poorer and more rocky ground.

Fruit harvest and processing

Most olives today are harvested by shaking the boughs or the whole tree. Another method involves standing on a ladder and "milking" the olives into a sack tied around the harvester's waist. Using olives found lying on the ground can result in poor quality oil. In southern Europe the olive harvest is in the winter months, continuing for several weeks, but the time varies in each country, and also with the season and the kinds cultivated. A device called the oli-net wraps around the trunk of the tree and opens to form an umbrella like catcher to catch fruit that is picked. Workers can then harvest the fruit without the weight of the load around their neck. Another device, the oliviera, is an electronic tool that connects to a battery. The oliviera has large tongs that are spun around quickly, removing fruit from the tree. This method is used for olive oil variety olives. Table olive varieties are more difficult to harvest, as workers must take caution not to damage the fruit in any way. Picking baskets that hang around the worker's neck are used.

The amount of oil contained in the fruit differs greatly in the various cultivars; the pericarp is usually 60-70% oil. Typical yields are 1.5-2.2 kg of oil per tree per year.

Traditional fermentation

Olives freshly picked from the tree contain phenolic compounds and a unique glycoside, oleuropein, which makes the fruit unpalatable for immediate consumption. There are many ways of processing olives for table use. Traditional methods use the natural microflora on the fruit and procedures which select for those that bring about fermentation of the fruit. This fermentation leads to three important outcomes: the leaching out and breakdown of oleuropein and phenolic compounds; the creation of lactic acid, which is a natural preservative; and a complex of flavorsome fermentation products. The result is a product which will store with or without refrigeration.

One basic fermentation method is to get food grade containers, which may include plastic containers from companies which trade in olives and preserved vine leaves. Many bakeries also recycle food grade plastic containers which are well sized for olive fermentation; they are 10 to 20 liters in capacity. Freshly picked olives are often sold at markets in 10 kg trays. Olives should be selected for their firmness if green and general good condition. Olives can be used green, ripe green (which is a yellower shade of green, or green with hints of color), through to full purple black ripeness. The olives are soaked in water to wash them, and drained. 7 liters (which is 7 kg) of room temperature water is added to the fermentation container, and 800 g of sea salt, and one cup (300g) of white vinegar (white wine or cider vinegar). The salt is dissolved to create a 10% solution (the 800 g of salt is in a 8 kg mixture of salt and water and vinegar). Each olive is given a single deep slit with a small knife (if small), or up to three slits per fruit (if large, eg 60 fruit per kg). If 10 kg of olives are added to the 10% salt solution, the ultimate salinity after some weeks will be around 5 to 6% once the water in the olives moves into solution and the salt moves into the olives. The olives are weighed down with an inert object such as a plate so they are fully immersed and lightly sealed in their container. The light sealing is to allow the gases of fermentation to escape. It is also possible to make a plastic bag partially filled with water, and lay this over the top as a venting lid which also provides a good seal. The exclusion of oxygen is useful but not as critical as when grapes are fermented to produce wine. The olives can be tasted at any time as the bitter compounds are not poisonous, and oleuropein is a useful antioxidant in the human diet.

The olives are edible within 2 weeks to a month, but can be left to cure for up to three months. Green olives will usually be firmer in texture after curing than black olives. Olives can be flavored by soaking them in various marinades, or removing the pit and stuffing them. Herbs, spices, olive oil, feta, capsicum (pimento), chili, lemon zest, lemon juice, garlic cloves, wine, vinegar, juniper berries, and anchovies are popular flavorings. Sometimes the olives are lightly cracked with a hammer or a stone to trigger fermentation. This method of curing adds a slightly bitter taste.

Pests and diseases

A fungus Cycloconium oleaginum can infect the trees for several successive seasons, causing great damage to plantations. A species of bacterium, Pseudomonas savastanoi pv. oleae induces tumor growth in the shoots, and certain lepidopterous caterpillars feed on the leaves and flowers, while the main damage is made by the olive-fly attacks to the fruit. In France and north-central Italy olives suffer occasionally from frost. Gales and long-continued rains during the gathering season also cause damage. Another pest which spreads through olive trees is the black scale bug. Black scale is a small black beetle that resembles a small black spot. They attach themselves firmly to olive trees and reduce the quality of the fruit. The main predator of black scale is wasps.

Economy

Olive output in 2005

Production

Olive is the most extensively cultivated fruit crop in the world. Its cultivation areas has tripled in the past 44 years, passing from 2.6 to 8.5 million of hectares.

The first ten countries of production, as per FAO, all located in the Mediterranean region, represent together 95% of the world production of olives.

Main countries of production (Year 2003)

Rank	Country/Region	Production (in tons)	Cultivated area (in hectares)	Yield (q/Ha)
—	World	17,317,089	8,597,064	20.1
1	Spain	6,160,100	2,400,000	25.7
2	Italy	3,149,830	1,140,685	27.6
3	Greece	2,400,000	765,000	31.4
4	Turkey	1,800,000	594,000	30.3
5	Syria	998,988	498,981	20.0
6	Tunisia	500,000	1,500,000	3.3
7	Morocco	470,000	550,000	8.5
8	Egypt	318,339	49,888	63.8
9	Algeria	300,000	178,000	16.9
10	Portugal	280,000	430,000	6.5
11	Lebanon	180,000	230,000	4.5

Olive as an invasive weed

Since its first domestication, Olea europaea has been spreading back to the wild from planted groves. Its original wild populations in southern Europe have been largely swamped by feral plants.

In some other parts of the world where it has been introduced, most notably South Australia, the Olive has become a major woody weed that displaces native vegetation. Its seeds are spread by the introduced Red Fox and by many bird species including the European Starling and the native Emu into woodlands where they germinate and eventually form a dense canopy that prevents regeneration of native trees.

See also

• Oil-tree
• Olive (fruit)
• Phytonutrient
• Polyphenol antioxidant
• Olive leaf

External links

• The Olive Tree World. Retrieved November 7, 2007.
• Olive germplasm. Retrieved November 7, 2007.
• Plants for a Future: Olea europaea. Retrieved November 7, 2007.
• The history and gastronomy of the olive and olive oil in Spain. Retrieved November 7, 2007.
• Greek Olives and Olive Oil: History, cultivation, production and marketing. Retrieved November 7, 2007.
• How to pickle olives. Retrieved November 7, 2007.
• Pickling Olives the Mediterranean Way. Retrieved November 7, 2007.

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