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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. |
