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Olive
(Olea europea L.)
Olive is one of the most important cultigens and played in exceptionally
significant rôle in the ancient civilisations around the Mediterranean
sea: Egyptians, Phoenicians, Greeks and Romans knew and valued olive
oil. The olive tree is mentioned in the Homeric epics and olive branches
were used, in oldest time, to decorate the winners of the Olympic
Games; later, they were replaced by bay leaves. In the classic era
of Greece, the olive was closely associated with the goddes Pallas
Athene, a daughter of Zeus. Innumerous are the instances of olive
in the Bible, both in the Old and the New Testament. The old Romans
used olive oil extensively.
Olives are grown in the whole Mediterranean region and are a most
important part of the diet in all Mediterranean countries: Olive oil
is ubiquitously used as a cooking medium, and pickled olives are popular
both a spice and as a snack.
Pickled olives are either black or green, depending whether they have
been harvested unripe or ripe. Green olives are plucked unripe and
either repeatedly watered or treated with concentrated lye before
pickling; by the latter procedure, which dates back to ancient Rome,
bitterness is greatly reduced and the texture is improved. Black olives
are plucked ripe; in Greece, they are treated with salt or undergo
lactic fermentation, which results in an intense flavour. The brine
olives are pickled in is often further enhanced by addition of some
herbs.
Far more important than pickled olives is, however, olive oil, whose
production consumes about 90% of olive acreage. The best quality,
native olive oil extra (formerly known by the Italian term extra vergine),
is quite variable in appearance and taste; after having tried some
oils, most people develop different preferences. Some oils are subtle
and flowery, others intense and fruity. It is probably a good idea
to stock a few different varieties in the kitchen.
There is a huge variety in olive oils, both regarding colour and flavour.
The multitude of olive oil qualities can, essentially, be reduced
to two factors: Quality of the underlying olives, and method of extraction.
Used plant part
The fruit (a drupe), which is pale green when unripe and purple to
black when ripe. Most olive fruits are harvested for the extraction
of olive oil; only a small fraction goes into the production of pickled
olives. The leaves of the olive tree are used medicinally for their
hypotensive qualities.
Plant family
Oleaceae (olive family).
Sensoric quality
Raw unripe olives are very bitter; to make them palatable, the bitter
constituents are reduced by treatment with lye. Ripe olives, on the
other hand, can be directly preserved in salt or brine. Olive oil
has a very variable flavour. The best oils can have mild or strong
flavour that ranges somewhere between “floral”, “fruity”
or “fresh”. Poor qualities have pungent, acidic, rancid
or even no aroma.
Main constituents
In leaves and fruits of the olive tree, a phenolic seco-iridoid called
oleuropein is found; it is the hypotensive principle. Before pickling
olives, the oleuropein is removed either by treatment with lye or
by lactic fermentation; the remaining residues of oleuropein are sometimes
said to prevent diseases resulting from high blood pressure.
Olive oil is obtained from the mesocarp of special varieties of olives
with rather small fruits; the mesocarp contains about 55% of oil
Origin
Cultivation of the olive tree is known in the Eastern Mediterranean
since five millennia. Whether the plant really stems from these regions
or is a native to Central Asia is subject to debate. |