Olive
For alternate senses of this word see olive (disambiguation).The olive has been used since ancient times for the making of
olive oil and for eating of the
fruit, which, being bitter in its natural state, are typically subjected to
fermentation or cured with
lye or
brine to be made more palatable.
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 and by the earliest
poets. The ancient agriculturists believed that the Olive would not succeed 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 less severe.
Muhammad also mentions that the tree is blessed and recommends consumption and anointment of
olive oil.
Olives are now culivated in many regions of the world such as
South Africa,
Australia,
New Zealand, and
California. Considerable research has been done to support the health benefits of eating olives and olive oil (see external links below for research results).
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
|
A young olive plant, germinated from a seed |
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 that are 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 flavour while Frantoio is fruity with a stronger aftertaste. Due to their highly valued flavour, 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 big size, 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 oil of exceptional quality.
* 'Picholine' originated in the south of
France. It is green, medium size, and elongated. Their flavour is mild and nutty.
* 'Lucques' originated in the south of France. They are green, of a large size, and elongated. The bone has an arcuated shape. Their flavour is mild and nutty.
* 'Souri' originated in Lebanon and is widespread in Israel and neighboring countries. It has a high oil yield and exceptionally aromatic flavour.
* '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 flavour 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, Israeli cultivar derived from the North African 'Chemlali' cultivar. The olive is medium sized, round, has a fruity flavour and can be used for oil or for table olives.
*'Vacaca' is an odiferous cultivar that is mostly found in the Southwest.
Growth and propagation
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 favourable 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 centimetres 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. Lax practices such as using olives 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.
The amount of oil contained in the fruit differs much in the various sorts; the pericarp usually yields from 60 to 70%.
Traditional Fermentation of Table Olives
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 flavoursome 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 litres in capacity. Olives are often sold at markets in 10kg 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 colour), through to full purple black ripeness. The olives are soaked in water to wash them, and drained. About 7 litres of room temperature water is added to the fermentation container, and 800g 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 800g of salt is in a 8kg mixture of salt and water and vinegar). Each olive is given a single deep slit with a small knife if they are small, or up to three slits per fruit if they are 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 tested at any time as the bitter compounds are not poisonous. Oleuropein is a useful antioxident in the human diet. The olives become reasonably acceptable after 2 weeks to a month, and may develop full maturity in three months. This is happening in winter as they are harvested in autumn. Green olives should be firm in texture once fermented and black olives will be softer. Olives produced in this way will normally be be safe and delicious as is. Should you want to present your olives with other flavours they can be marinated in, or stuffed with, a great variety of herbs, spices, and flavours such as additional olive oil, fetta, capsicum (pimento), chili, lemon zest, lemon juice, wines, vinegars, and anchovies. This method has many variations and may include longer washes in water, up to a week, and multiple changes of salt solution.
A
fungus Cycloconium oleaginum can infect the trees for several successive seasons, causing great damage to plantations. A species of
bacterium,
Pseudomonas savastanoi pv.
savastanoi induces tumour 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.
*
Phytonutrient*
Polyphenol antioxidant* [
1]
*
Olive at Plants for a Future*
International Olive Oil Council Includes studies on health benefits
*
The California Olive Oil Council*
Resource portal for olive oil*
The history and gastronomy of the olive and olive oil in Spain *
Medical uses *
Australian Olive Association Association growing, harvesting and processing factsheet
