VANILLA, a flavouring agent largely used in the manufacture of chocolate, in confectionery, and in perfumery. It consists of the fermented and dried pods of several species of orchids belonging to the genus Vanilla.1 The great bulk of the commercial article is the produce of 1 Span, vainilla, dim. of vaina, a pod.
V. planifolia, Andrews, a native of eastern Mexico, but now largely cultivated in several tropical countries, especi-ally in Reunion, the Seychelles, and Java. The plant has a long fleshy stem and attaches itself by its aerial rootlets to trees, and appears to be little dependent on the soil for nourishment. The leaves are alternate, oval-lanceolate, and fleshy; and the greenish white flowers form axillary
Vanilla plant. A. Flower, leaf, and aerial rootlets. B. Pod or fruit.
spikes. The fruit is a pod from 6 to 12 inches long, and when mature about half an inch in diameter. The wild plant yields a smaller and less aromatic fruit, distinguished in Mexico as Baynilla cimarona, the cultivated vanilla being known as B. corriente. Mexican vanilla is regarded as the best. It is principally consumed in the United States, which import about 100,000 lb of it annually. Reunion produces about the same quantity, which is sent to Bordeaux, the chief centre of the trade in France. Its odour is said to differ from the Mexican variety in having a suggestion of tonqua bean. Guadaloupe produces about 5000 lb per annum, which is likewise shipped to Bordeaux. Mauritius exported 20,481 ft in 1877. The Seychelles have lately produced large quantities of exceedingly fine quality; the produce of these islands goes chiefly to the London market. The Java vanilla, grown chiefly in Kra-wang and the Breanger Begencies, is shipped to Holland. The amount exported from the East Indian Archipelago to Holland in 1876 amounted to about 50001b. The best varieties of vanilla pods are of a dark chocolate brown or nearly black colour, and are covered with a crystalline efflorescence technically known as givre, the presence of which is taken as a criterion of quality. The peculiar fragrance of vanilla is due to vanillin, C8H803, which forms this efflorescence. Chemically speaking, it is the aldehyde of methyl-protocatechuic acid. It is not naturally present in the fleshy exterior of the pod, but is secreted by hair-like papillas lining its three internal angles, and ultimately becomes diffused through the viscid oily liquid surround-ing the seeds. The amount of vanillin varies according to the kind : Mexican vanilla yields 1 '69, Bourbon or Reunion 1*9 to 2-48, and Java 2-75 per cent. Besides vanillin, the pods contain vanillic acid (which is odourless), about 11 per cent, of fixed oil, 2'3 per cent, of soft resin, sugar, gum, and oxalate of lime.
Vanillin forms crystalline needles, fusible at 81° C, and soluble in alcohol and ether, hardly soluble in cold, but more so in boiling water. Like other aldehydes, it forms a compound with the alkaline bisulphites, and can by this means be extracted from bodies containing it. Vanillin has been found in Siam benzoin and in raw sugar, and has been prepared artificially from coniferin, a substance found in the sapwood of fir-trees, from asafcetida, and from a con. stituent of oil of cloves named eugenol. It is from the last-named that vanillin is now prepared on a commercial scale, chiefly in Germany. Vanillin does not appear to have any physiological
action on human beings when taken in small doses, as much as 10 to 15 grains having been administered without noxious results. On small animals, however, such as frogs, it appears to act as a con-vulsive. It has been suggested as a stimulant of an excito-motor character in atonic dyspepsia. The poisonous effects that have on several occasions followed from eating ices flavoured with vanilla are not to be attributed to the vanilla, but probably to the presence of tyrotoxicon (Pharm. Journ. , xvii. p. 150), a poison found in milk which has undergone certain putrefactive changes, and producing choleraic effects, or perhaps to the presence of micro-scopic fungi in the vanilla, the plantations being liable to the attack of Bacterium putredinis. Workmen handling the beans in the Bordeaux factories are subject to itching of the hands and face ; but this is caused by an Acarus wdiich occupies the end of the pod. In some cases, however, symptoms of dizziness, weariness, and malaise, with muscular pains, have been felt, due probably to the absorption of the oily juice by the hands of the workmen. These symptoms have been attributed to the variety of vanilla known as vanillon, but it seems equally probable that they are due to idiosyncrasy.
The method of cultivation and preparation of vanilla for the market varies somewhat in different countries. In Mexico a clear-ing is made in the forest, where a few young trees, 12 or 15 feet apart, are left to serve as a support for the climbing stems of the vanilla plant. Close to each tree two cuttings, 3 to 5 feet in length, are inserted in the soil to the depth of about a foot, the upper part being tied to the tree. The cuttings become rooted in about a month, but do not bear fruit until the third year. They continue to bear for about thirty years. In Reunion, Mauritius, and the Seychelles the young plants are supported by a rude trellis made between the trunks of trees. Although the plants are probably fertilized by insects in their native country, in Reunion and else-where fertilization has to be promoted by hand. Only the finest flowers of each spike are fertilized, or the plants would die of exhaustion. The pods are cut off separately as they ripen, since, if over-ripe, they are apt to split in drying, and if unripe the product will be of inferior colour and fragrance. The pods take a month to arrive at full size and six months longer to ripen. The exact time for collecting is judged by the crackling of the pod when pinched between the fingers. The aroma of vanilla is developed by fermentation, and is said not to pre-exist in the ripe fruit.
In Mexico the pods, after they are gathered, are placed in heaps under a shed until they begin to shrivel, and are then submitted to a sweating process. They are next wrapped in a woollen cloth and exposed to the sun during the day, or heated in an oven to 140" Fahr. if the weather is cloudy, and then enclosed in air-tight boxes at night to sweat. In twenty-four to thirty-six hours, accord-ing to size, the pods have acquired a fine chestnut-brown colour. They are then spread in the sun for about two months to dry, and are subsequently tied up into small packets of uniform length. In Reunion the pods are sorted into lengths and scalded in boiling water, the long pods being immersed ten seconds, those of a medium size fifteen seconds, and the short ones for fully one minute. They are next exposed to the sun between woollen blankets for about a week, until they assume the characteristic brown colour. They are then spread out under zinc-roofed sheds and turned frequently to ensure equal drying. When the beans can be twisted round the finger without cracking, the " smoothing process " is commenced. This consists in passing the beans between the fingers frequently, apparently to distribute equally the unctuous liquid which exudes as the fermentation proceeds, and to which the lustre and supple-ness of the bean are due. When dry they are tied up in bundles of uniform length. These are divided into three commercial sorts,(1) those which are nearly black and glossy and which soon become frosted ; (2) those which are lighter in colour, more or less spotted with grey, and not so glossy ; (3) those which are gathered in an unripe condition and become little, if at all, frosted over with crystals. In Guiana, where an inferior quality is prepared, the beans are placed on ashes and left until they begin to shrivel; they are then wiped, rubbed over with oil, and, the lower end of the pod having been tied, are hung up in the air to dry.
Other Varieties.In Brazil, Peru, and other parts of South
America a broad and fleshy vanilla is prepared, wdiich has an inferior
odour. It is believed to be obtained from V. pompona, Schiede,
which has been found to contain, besides from '4 to -7 per cent, of
vanillin, another ingredient, benzaldehyde, by which the odour of
vanilla is modified. This variety is often distinguished as vanillon
in commerce. It is destitute of givre. Rio vanilla is collected
on the banks of the Parahyba river in the province of Rio de
Janeiro, Brazil, and is obtained from V. palmarum, Lindl. It has
been found to yield 1*03 per cent, of vanillin. It is of inferior
quality, but might be improved if more attention were paid to
the curing process. Guiana vanilla is a coarse variety obtained
from V. guianensis, Splitberger. The pods are short, thick, and
frequently split open, and of inferior fragrance. None of the South-
American vanillas appear to be used in Great Britain for flavouring
purposes, but solely for perfumery. (E. M. H.)