The wood of the olive tree is much prized for certain purposes. It is very close, fine-grained, yellow to yellowish brown with irregular wavy brown to black lines and mottlings, especially near the root. It has no distinguishable annual rings or pith rays, and has evenly distributed vessels. It takes a beautiful polish. At present it is employed chiefly in lathe-work and carving for small fancy articles, and for cabinet work.
In ancient times it seems to have had a much wider application, due no doubt to the size of the trees, which were larger as a result of not being subjected to the rigorous cultivation and pruning which they receive today. The Bible states that olive wood was used in the Temple. In the time of Pliny it furnished material for construction of ships, for wagon spokes, wedges, columns, pedestals, statues, and furniture. The Romans used both the wild and cultivated trees. The wood industry was developed in the vicinity of Nice in both France and Italy, and still flourishes. A considerable amount has been exported to England in recent years for the manufacture of walking sticks. The poorer quality is used for firewood, is inflammable, and produces great heat.
BARK
The bark contains a large amount of tannin. For medicinal purposes it is reduced to powder and acts as an astringent, a tonic, and a febrifuge. In warm climates a resin is exuded from it which solidifies in the air. It is called Lecca gum, as it was first found near Lecca. It contains some benzoic acid among other constituents and in ancient times was prescribed in medicine, but is not at present, and the gum is considered valueless.
FRUIT
The fruit has been considered a choice food at all times. It has appeared at the feasts of epicures, both ancient and modern, as a relish, and to be eaten at the end of the repast as part of the dessert, and at all times it has also furnished a staple food for the poor in the Orient and in Greek and Latin countries. Those who were well provided were admonished to have care for those less fortunate: “When thou beatest thine olive tree, thou shalt not go over the boughs again; it shall be for the stranger, for the fatherless, and for the widow.” (Deuteronomy XXIV., 20.) The people obliged to live frugally have found it a great resource, particularly in Lent and for those at a distance from the sea unable to obtain fresh fish. It is said that Plato preferred olives to all other foods, and often made a meal on them alone.
Though olives are known and consumed throughout the civilized world, comparatively few persons, aside from those living in the regions of their cultivation, know that olives have to undergo certain treatment before they can be eaten. It is a common practise in olive regions to encourage the visitor to taste the fruit directly from the tree. The fruit, both green and black, looks so fine and tempting, that the disgust on tasting is correspondingly great. It is claimed that some of the older varieties could be eaten without preparation, that they dried naturally, and were sweet like raisins.
The olive contains a bitter and acrid substance or substances which must be removed before the olives are edible. It is referred to in most of the literature as a “bitter principle”, and has been called an acid, a tannin, and more recently a glucoside. Cruess has repeated the work of the various investigators, who claimed these different substances, and as a result has come to the conclusion that it is a glucoside, that is, a combination of glucose with another compound.
In immature fleshy fruits there is usually an accumulation of acids, tannins, and sometimes starch. As ripening proceeds, carbohydrates and aromatic substances are formed, and the bitter, acrid, or astringent taste disappears. In the olive there is no starch found at any stage of maturity. Glucose has been found in all stages, and is supposed to be the substance from which the oil is formed. The oil is in very minute quantities in the fruit up to the time when the pit is formed, from then on it increases gradually up to its maximum when the fruit is not quite mature. In the plant economy the fat or oil is one of the most important food reserves of plants. All parts of the fruit—rind, flesh, stone, and seed—contain oil, the fleshy part, forming about 80% of the fruit, containing the largest amount.
Contrary to the condition existing in most fruits, the bitterness remains through all stages of development in the olive. A substance of glucosidic nature, given the name “oleuropeine”, has been isolated, and found to be of extreme bitterness. This may be the substance or one of the substances which cause the inedibility of the untreated olive.