Botanical Origin—Citrus Bergamia var. vulgaris Risso et Poiteau,[472] a small tree closely resembling in flowers and foliage the Bitter Orange. Its fruit is 2½ to 3 inches in diameter, nearly spherical, or slightly pear-shaped, frequently crowned by the persistent style; it is of a pale golden yellow like a lemon,[473] with the peel smooth and thin, abounding in essential oil of a peculiar fragrance; the pulp is pale yellowish green, of a bitterish taste, and far less acid than that of the lemon.
The tree is cultivated at Reggio in Calabria, and is unknown in a wild state.
History—The bergamot is one of the cultivated forms which abound in the genus Citrus, and which constitute the innumerable varieties of the orange, lemon and citron. Whether it is most nearly related to the lemon or to the orange is a point discussed as early as the beginning of the last century. Gallesio[474] remarks that it so evidently combines the characters of the two that it should be regarded as a hybrid between them. The bergamot first appeared in the latter part of the 17th century. It is not mentioned in the grand work on orange trees of Ferrari,[475] published at Rome in 1646, nor in the treatise of Commelyn[476] (1676), nor in the writings of Lanzoni (1690),[477] or La Quintinie (1692).[478] So far as we know, it is first noticed in a little book called Le Parfumeur François, printed at Lyons in 1693. The author who calls himself Le Sieur Barbe, parfumeur, says that the Essence de Cedra ou Bergamotte is obtained from the fruits of a lemon-tree which has been grafted on the stem of a bergamot pear; he adds that it is got by squeezing small bits of the peel with the fingers in a bottle or globe large enough to allow the hand to enter.
Volkamer of Nuremberg, who produced a fine work on the Citron tribe in 1708, has a chapter on the Limon Bergamotta, which he describes as gloria limonum et fructus inter omnes nobilissimus. He states that the Italians prepare from it the finest essences, which are sold at a high price.[479]
But, as shown by one of us,[480] the essential oil of bergamot had already, in 1688, a place among the stores of an apothecary of the German town of Giessen.
The name Bergamotta was originally applied to a large kind of pear, called in Turkish “beg-ârmûdî,” i.e. prince’s pear.[481]
Production—The bergamot is cultivated at Reggio, on low ground near the sea, and in the adjacent villages. The trees are often intermixed with lemon and orange trees, and the soil is well irrigated and cropped with vegetables.
The essential oil (Oleum Bergamottæ) is obtained from the full-grown but still unripe and more or less green fruits, gathered in the months of November and December. They are richer in oil than any one of the allied fruits. It was formerly made like that of lemon by the sponge-process, but during the last 20 years this method has been generally superseded by the introduction of a special machine for the extraction of the essential oil. In this machine the fruits are placed in a strong, saucer-like, metallic dish, about 10 inches in diameter, having in the centre a raised opening which with the outer edge forms a broad groove or channel; the dish is fitted with a cover of similar form. The inner surface both of the dish and cover is rendered rough by a series of narrow, radiating metal ridges of blades which are about ¼ of an inch high and resemble the backs of knifes. The dish is also furnished with some small openings to allow of the outflow of essential oil; and both dish and cover are arranged in a metallic cylinder, placed over a vessel to receive the oil. By a simple arrangement of cog-wheels moved by a handle, the cover, which is very heavy, is made to revolve rapidly over the dish, and the fruit lying in the groove between the two is carried round, and at the same time is subjected to the action of the sharp ridges, which, rupturing the oil-vessels, cause the essence to escape, and set it free to flow out by the small openings in the bottom of the dish. The fruits are placed in the machine, 6, 8, or more at a time, according to their size, and subjected to the rotatory action above described for about half a minute, when the machine is stopped, they are removed, and fresh ones substituted. About 7,000 fruits can thus be worked in one of these machines in a day. The yield of oil is said to be similar to that of lemon, namely 2½ to 3 ounces from 100 fruits.
Essence of bergamot made by the machine is of a greener tint than that obtained by the old sponge-process. During some weeks after extraction it gradually deposits a quantity of white greasy matter (bergaptene), which, after having been exhausted as much as possible by pressure, is finally subjected to distillation with water in order to separate the essential oil it still contains.
The fruits from which the essence has been extracted are submitted to pressure, and the juice, which is much inferior in acidity to lemon juice, is concentrated and sold for the manufacture of citric acid. Finally, the residue from which both essence and juice have been removed, is consumed as food by oxen.