Characteristics of the Olive Tree and Olive Fruit

Characteristics of the Olive Tree and Olive Fruit Dimitrios Boskou Laboratory of Food Chemistry and Technology School of Chemistry, Aristotle University of Thessaloniki University Campus, Thessaloniki, 54124, Hellas, Greece Tel. 0030 3210 997791 Fax 0030 2310 997779

History of the Olive Tree Olive is the common name for about 35 species of evergreen shrubs and trees of the genus Olea in the olive family, the Oleaceae, native to tropical and warm temperate regions. e name is especially used for Olea Europaea, the well-known olive which is grown for its edible fruits. Olive trees are native to Greece, Italy, Palestine, and Syria, but different species are native to different areas. It is believed that cultivation of olives started around the fourth millennium B.C. in the area which is today Syria and Palestine. e inhabitants of Crete during the Minoan civilization cultivated olives as early as 2500 B.C. Pottery items such as jars found in Knossos Palace were probably intended for storing olive oil. e botanical origin of the tree and the beginning of its cultivation have been a subject of dispute (Anon, 1983, Loukas and Krimbas, 1983, Blazquez,1996). Archeologists tend to believe that the transformation to the cultivated tree should be placed in the early Bronze Age. During this period management of olive populations consisting of intentional and selective pruning have been probably applied by man to rejuvenate olive tree in order to favor flowering and fruit production. From the 35 known species of the genus olea the one that is considered to be the ancestor of olive oil is O. Chrysophylla, found in Asia and Africa. ere is, however, another theory according to which the progenitor is the Mediterranean wild olive, olea oleaster (Loukas and Krimbas, 1983). Others consider olea oleaster as an intermediate in the development from the wild olive tree olea chrysophylla to olea europaea (Blazquez,1996, Lavee,1996). e spread of the olive tree to western places is due to Phoenicians who traded with other maritime centers. From the sixteenth century B.C., the tree began to reach the Greek islands and also Libya and Carthage. e Greeks extended olive farming and spread it through their colonies and routes taken by their seamen. e island of Samos was called “Elaeophytos,” which means “planted with olives.” e first sig-

nificant improvement of olive cultivation and a better organization occurred in the seventh century B.C. (Fiorino and Nizzi Griffi, 1992). Later, the Romans discovered olive trees through their contacts with the Greek colonies in Italy. Although they were not admirers of olives and olive oil, the Romans expanded the tree throughout the huge empire. ey used olive oil in their baths and as a fuel, but, for edible purposes, they considered it as a commodity of moderate quality. e rise of the Roman Empire and the conquest of Greece, Asia Minor, and Egypt increased the trading channels around the Mediterranean Sea and olive oil became far more important, not only as a staple food, but also as a pharmaceutical and a source of energy (Chazau-Gilling, 1994). Expansion of olive growing continued until the fifth century A.D. and revived again when maritime cities began to grow. Between the twelfth and sixteenth century A.D., an impressive advance of olive oil orchards was observed in Italy (Fiorino and Nizzi-Griffi, 1992). When America was discovered, missionaries and early settlers introduced wine and olive trees to the New World. Wine spread everywhere, but olive trees were cultivated only in restricted areas in Chile, Argentina, and California. During the nineteenth century, olive farming reached a peak because lighting was still based on fatty substances, and oil seeds were not known enough to be exploited as sources of edible oils as they are today. e cultivation of the olive tree has now been extended to many regions of the world where climatic and other conditions are as favorable as those prevailing in the Mediterranean countries. Until the advent of present-day propagation and cultivation techniques, olive trees usually began to crop after their eighth year. ey could live to an age of several centuries and there are claims that olive trees exist with an age of more than one thousand years. One explanation for this longevity is its characteristic ability to send out shoots and roots from temporary buds which are abundant at the lower part of the trunk. e root system of the tree tends to spread horizontally rather than downwards. e tree is resistant to adverse conditions and adapts to all kinds of soils (even poor soils that cannot be used for other crops). It can sprout even if the part above the soil is seriously wounded. It can also tolerate dryness and lack of treatment better than most other fruit trees. e olive tree is a broad evergreen tree. Depending on the subspecies and environmental conditions, its height may vary from 3 to 20 meters. e cost of modern cultivation and harvesting has made low shapes (4-5 meters in height) very popular to farmers in many olive-producing countries. e trunk of the young tree is smooth with a green color, but later it becomes uneven and tends to twine and often hollow with the passing of time. e bark, greenish-gray in young trees, becomes dark gray as the tree grows older. e flowers are small, yellow-white, and appear in erect clusters. e leaves are narrow, lanceloate, leatherish, and persistent (they stay on the tree for 3 years). eir color is green above and silky white beneath.