Vanilla (U. S. P.)—Vanilla.
"The fruit of Vanilla planifolia, Andrews"—(U. S. P.).
COMMON NAME: Vanilla.
ILLUSTRATION: Bentley and Trimen, Med. Plants, 272.
History and Botanical Source.—The plant which produces vanilla bean is an orchid, native of the tropical forests of Mexico, but now grown in many other parts of the globe, as in Brazil, Honduras, Java, Africa, and the West Indies, though only on the island of Guadaloupe on a commercial scale. Vanilla has probably been in use among the Mexicans from times immemorial, as a flavor to their chocolate, and was made known to the western world by the Spaniards. Hernandez, the Spanish historian, describes it under the botanical name Aracus aromaticus, also mentioning its Mexican name, Tlilxochitl. Clusius, in 1602, calls it Lobus oblongus aromaticus. The generic name of the plant was established, in 1752, by Plumier, and the present name of the species yielding the true Mexican vanilla of commerce, by Andrews, in 1808. (As to priority of synonyms, see George M. Beringer, Amer. Jour. Pharm., 1895, p. 611.) While the Index Kewensis enumerates 34 species of vanilla; only very few contribute to the world's supply of the vanillas of commerce—for example, V. planifolia, Andrews (Mexico, also cultivated in Réunion, Java, etc.); V. pompona, Schiede (southeast Mexico, Panama, Colombia, Venezuela, Surinam, Cayenne, Guadaloupe, etc.); and V. Gardneri, Rolfe (Brazil) (R. A. Rolfe, Kew Bulletin, 1895, p. 169; see Beringer, loc. cit.).
Vanilla planifolia, Andrews, the official source of the bean, is a climbing vine, with a thick, succulent stem, and entire, thick, smooth, bright-green, pointed leaves, 4 to 9 inches long, and 1 1/2 to 2 1/2 inches broad. Opposite the leaves, it is furnished with numerous aerial roots, with which it clings to its support. The flowers are produced in axillary bunches of 8 or 10; they are of a pale-yellow color, about 2 inches in diameter, have the usual orchidaceous structure, but are more regular in appearance than most orchids. The fruit is a pendant pod, 5 to 10 inches long, and an inch or more in circumference when fresh, and contains myriads of minute seeds. These pods, when properly cured and dried, are the vanilla of commerce. Regarding the mode of sustenance of the vanilla vine, two statements have been made—one, that it is a parasite, deriving its nourishment from the tree to which it clings; the other, that it is an epiphyte (as many orchids are), i. e., living entirely on moisture and nourishment derived from the air. Neither opinion is exact. After the vanilla plant has established itself, it will continue to grow even if its connection with the ground is severed, and will throw out new roots, which reach and penetrate the ground. Hence it is, to some extent, epiphytic. But should it fail to establish its connection with the ground, it will finally wither and die. It is in no sense a parasite.
Cultivation and Treatment.—Vanilla is almost exclusively propagated from cuttings, although it can be reared from seeds, but not without considerably delaying the year of the harvest. A warm and moist climate, sandy, moist (not marshy) soil, a mixture of shade and sunshine, the shade predominating, is essential to its successful cultivation. The temperature should average from 75° to 80° F., but should not fall below 65° F. in winter, and the plants should be protected from the salty air of the ocean breezes. If a virgin forest is to be transformed into a vanilla plantation, all superfluous shade must be removed, while, when an open field is to be cultivated, shade trees must first be planted. After about 4 weeks, the cuttings will have taken root, and, in the third year, they begin to bear fruit, and continue to bear for a period of from 30 to 40 years, although with decreasing tendency after the tenth year. In Mexico, the vanilla is permitted to climb the highest trees, while, in Réunion, the expanding vines are so guided as to permit of easy access.
Like most orchids, vanilla depends on insects for fertilization, but in Réunion, where these are absent, artificial fecundation must be resorted to. This is done by slipping aside the labellum, a dividing film, which separates the anther from the stigma, and pressing them lightly together. Care must be taken not to produce, in this way, too many fruits on one stalk, because, in this case, the plants would perish before the pods could ripen. The vine blossoms from March to June, the pod, however, does not ripen until the following January or February. Unfortunately, vanilla in Mexico is picked before it ripens—namely, as early as October or November, chiefly because the crop is in danger of being stolen. This pernicious habit was noticed as early as 1811 by Humboldt.
The value of vanilla depends greatly on the success of the curing process, which requires much skill and experience on the part of the operator. During this manipulation, the flavor of the bean is developed by a peculiar sweating process, a mode of fermentation, which causes the bean to shrivel and to assume a fine chestnut-brown color. This process is carried out differently in different vanilla-producing countries. Ripe vanillas can be cured much more easily than those that are unripe, and the flavor is more permanent. First-grade ripe pods, when stored, become covered with crystals of vanillin in a few months, while the pods, when gathered green, do not form crystals, and are difficult to preserve (Charles E. Hires). The beans are finally sorted into different commercial grades, made into bundles, packed, and conveyed to the shipping ports. (For much interesting information regarding the cultivation and treatment of vanilla, see J. C. Sawer, Odorographia, Vol. I, 1892, pp. 143-173, London; and Charles E. Hires, "A Talk on Vanillas," in Amer. Jour. Pharm., 1893, pp. 571-584; also see a summary on vanilla, with indication of literature, by J. U. Lloyd, West. Drug., Dec., 1897.)
Description and Commercial Varieties.—The most valued of the vanillas of commerce is the MEXICAN VANILLA. It is the official kind, and is described by the U. S. P. as "from 15 to 25 Cm. (6 to 10 inches) long, and about 8 Mm. (1/3 inch) thick, linear, narrowed, and bent or hooked at the base, rather oblique at the apex, wrinkled, somewhat warty, dark-brown, glossy-leathery, 1-celled, and containing a blackish-brown pulp, with numerous minute seeds, and more or less acicular crystals; odor and taste peculiar, fragrant"—(U. S. P.). Mr. Beringer (On Some Commercial Vanillas, Amer. Jour. Pharm., 1892, pp. 289-294) remarks that the pods of this variety feel firmly plump, and there is a roughness to the touch, which becomes more pronounced as it gets older and dryer. While fresh, the surface is somewhat viscid; the crystals begin to form at the ends, and gradually extend over the surface.
BOURBON VANILLA, from the island of Réunion, is darker than the Mexican bean, and feels smooth and waxy. The odor, while not unpleasant, rather resembles that of tonka bean than Mexican vanilla. Good Bourbon vanilla is likewise covered with crystals ("frosted").
SEYCHELLES AND MAURITIUS VANILLA are sold as inferior Bourbon vanilla in the American market. They are of small size (about 6 inches), pale, smooth, non-waxy, and but faintly odorous.
SOUTH AMERICAN VANILLAS are reddish-brown in color, very pulpy, resinous, and scarcely frosted. Their odor is unpleasant, resembling that of fermented molasses.
TAHITI VANILLA is similar to the former. Its market is the Pacific coast and the western states.
WEST INDIAN VANILLONS, derived from V. pompona, Schiede, are exported from Martinique and Guadaloupe, and are collected also from wild vanillas in Mexico. They are only 4 to 5 inches in length, of a twisted appearance, owing to their being tied with twine during the process of curing. The odor is different from vanilla, and, as stated by Beringer (loc. cit.) may be compared to a cross between a fermented sugar and heliotrope odor. They are used in the tobacco industry, and, in perfumery, for sachet powders.
Chemical Composition.—The fragrance of vanilla is due to crystallizable vanillin, and a small quantity of a balsam, both of which are developed during the curing process. The presence of an odorous resin tends to impair the quality of the bean, according to its quantity. (For a complete analysis of vanilla beans, see W. von Leutner, Jahresb. der Pharm., 1872, p. 36, from Pharm. Zschr. f. Russland, 1871.) The" frost" which forms upon vanilla beans, upon storing, was formerly believed to be benzoic acid, until Gobley, in 1859, pointed out its distinction from the latter, and named it vanillin. He obtained it by treating an alcoholic extract of vanilla with ether, and recrystallizing the ether extract from hot water with the use of animal charcoal.
VANILLIN (C8H8O3) occurs in long, colorless needles, melting at 81° C. (177.8° F.), subliming at a higher temperature, and boiling in an atmosphere of carbon dioxide gas, without decomposition, at 285° C. (545° F.). It is little soluble in cold water (198 parts), much more soluble in boiling water (11 parts), and crystallizing upon cooling. It is easily soluble in ether, alcohol, and chloroform, very little soluble in low-boiling petroleum ether. The researches of Tiemann and Haarmann (1874-76) have shown vanillin to be methyl-proto-catechuic aldehyde, or, more exactly, meta-methoxy-para-oxy-benzoic aldehyde (C6H3[OH].[OCH3].CHO). Thus it is closely related to piperonal (C6H3[OCH3].[OCH3].CHO), of heliotrope odor (see Piperonal). These authors prepared vanillin synthetically from coniferin (C16H22O8+2H2O), a glucosid occurring in the cambium sap of coniferous trees; when treated with the ferment emulsin, it becomes hydrolyzed into dextrose and coniferyl alcohol, or oxy-eugenol (C10H12O3), which, upon oxidation, yields vanillin. The latter is now prepared synthetically by oxidation of eugenol (see Oil of Cloves, and diagram, by Prof. V. Coblentz, Journal of Pharmacology, 1898, p. 37). Or, it may be obtained from other similarly constituted compounds, e.g., creosol, guaiacol, caffeic acid, etc. Owing to its being an aldehyde, vanillin enters quantitatively into a crystallizable, ether-insoluble compound with sodium bisulphite (SO3HNa), from which vanillin may be regenerated by treatment with diluted acid (Tiemann and Haarmann). Another interesting aldehydic compound of vanillin is that with ammonia, which permits the quantitative separation of vanillin from coumarin, the aromatic principle of the tonka bean. "If vanillin be dissolved in pure, dry ether, and dry ammonia gas be passed through the solution, the aldehyde-ammonia compound of vanillin will be precipitated in almost quantitative proportions. * * * Coumarin, on the other hand, remains wholly (and unchanged) in the ether solution" (Wm. H. Hess and A. B. Prescott, Pharm. Review, 1899, p. 7). By oxidation, vanillin forms odorless, volatile vanillic acid, melting at 212° C. (413.6° F.). An alcoholic solution of vanillin produces greenish-blue with ferric chloride; an aqueous solution produces a permanent blue with the same reagent. It dissolves in sulphuric acid with yellow color.
The quality of commercial vanilla beans does not necessarily depend on the quantity of vanillin they contain; thus Tiemann and Haarmann found, in Mexican vanilla, 1.32 to 1.69 per cent, while Bourbon yielded from 0.75 to 2.9 per cent, and Java vanilla from 1.56 to 2.75 per cent of vanillin. Denner (1887) obtained 4.3 per cent from vanilla cultivated at Marburg (Flückiger, Pharmacognosie des Pflanzenreichs, 3d ed., 1891). West Indian vanillons contained 0.4 to 0.7 per cent of vanillin, together with a liquid aldehyde, probably benzoic aldehyde; when both are in prolonged contact with each other, an odor resembling heliotrope will be developed.
Benzoic acid, dusted over vanilla beans, with fraudulent intent, may be recognized, according to Messrs. Schimmel & Co. (1888), by abstracting the crystals with sodium carbonate, adding sulphuric acid and metallic magnesium or zinc; if the crystals are benzoic acid, the odor of oil of bitter almonds (benzoic aldehyde) will then be developed. Vanillin is also a constituent of many other vegetable products, such as Siam benzoin (Balsam of Peru, see H. Thoms, Archiv der Pharm., 1899), the sugar beet, asparagus, several kinds of wood, the husks of oats, etc.
Action, Medical Uses, and Dosage.—Aromatic stimulant. Vanilla is said to exhilarate the brain, prevent sleep, increase muscular energy, and stimulate the sexual propensities. Useful, in infusion, in hysteria, rheumatism, and low forms of fever. It is also considered an aphrodisiac, powerfully exciting the generative system. Much used in perfumery, and to flavor tinctures, syrups, ointments, confectionery, etc. Dose, of the powder, from 8 to 10 grains; of the infusion, made in the proportion of 1/2 ounce to 1 pint of boiling water, 1/2 fluid ounce, 3 or 4 times a day. To pulverize it, the pods must be cut in small pieces mixed with sugar, 4 parts, and pounded in an iron mortar, then sifted; the residue to be powdered with more sugar, and so on.
Related Plants.—A plant of the distinct genus SOBRALIA, collected by Prof. Rusby in the Andes, produces a pod which develops the odor of vanilla upon maturity (see Jour. of Pharmacol., 1898, p. 29); likewise, the flowers of a certain orchid, growing in Switzerland, yield considerable quantities of vanillin.
The Vanilla plant, or Southern vanilla, is the Liatris odoratissima, Michaux. The odorous principle of its leaves is coumarin (see Charles Falkenhainer, Amer. Jour. Pharm., 1899, p. 133; also see Liatris).
A similar odoriferous plant is Angraecum fragrans, Du Petit-Thouars, known in Mauritius and Réunion as faham. Its odoriferous principle is coumarin; its odor is that of vanilla, tonka, and melilot combined.