VANILLA, a flavouring agent largely used in the manu facture of chocolate, in confec tionery and in perfumery. It con sists of the fermented and dried pods of several species of orchids belonging to the genus Vanilla. The name of the genus comes from the Spanish Vainilla, a di minutive of vainer, a pod. The great bulk of the commercial article is the produce of V. plani f olia, a native of south-eastern Mexico, but now largely culti vatedin several tropical countries, especially in Bourbon, the Sey chelles, Tahiti and Java. The plant has a long fleshy stem and attaches itself by its aerial rootlets to trees; the roots also penetrate the soil. The leaves are alternate, oval-lanceolate and fleshy; the light greenish flowers form axillary spikes. The fruit is a pod from 6 to io in. long, 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 principally consumed in the United States. In Bourbon large areas are under cultivation; the crop 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 tonka bean.
The best varieties of vanilla pods are of a very 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 crite rion of quality. The peculiar fragrance of
vanilla is due to vanillin, C811803, which forms this efflorescence. Chemically speak ing, it is the aldehyde of methyl-protocate chuic acid. It is not naturally present in the fleshy exterior of the pod, but is secreted by hair-like papillae lining its three internal angles, and ultimately be comes diffused through the viscid oily liquid surrounding the seeds. Besides vanil lin, the pods contain vanillic acid (which is odourless), about I I% of fixed oil, 2.3% of soft resin, sugar, gum and oxalate of lime.
Vanillin forms crystalline needles, melt ing at 81° C, and soluble in alcohol, ether and oils, hardly soluble in cold, but more so in boiling water. Vanillin has been found in Siam benzoin and in raw sugar, and has been prepared artificially from coniferin, a glucoside found in the sapwood of fir-trees, from asafoetida, and from a constituent of oil of cloves named eugenol. It is now prepared synthetically on a commercial scale in Germany.