Vanilla is an exotic flavoring agent that is derived from the bean of the Vanilla Orchid. It is grown in very few places in the world (90% of the world’s vanilla is grown in Madagascar and Comoro and Reunion islands). The bean is cured and dried, allowing it to develop an exotic flavor. The chemical vanillin in the beans is primarily what gives the vanilla its flavor, though vanillin by itself does not actually taste very much like vanilla. It is the trace flavor compounds (the composition of which varies depending on where the vanilla is grown) which complement vanillin and give vanilla its distinctive flavor.
Natural vanilla flavor is created from the beans of vanilla plant. After a delicate growing and harvesting procedure the beans are treated with mild, moist heat in order to break down cell walls and promote enzymatic reactions. They are then sun, oven, and air dried for up to 6 months. During this curing process three types of glucosides are hydrolytically cleaved to produce phenols (one of which is vanillin, from glucovanillin) and glucose which give vanilla its characteristic flavor. After curing the beans are crushed and mixed with sugar. They are then percolated in an ethanol/water mixture for several weeks to extract the oils from the beans. The solids are filtered or centrifuged out and the alcohol content is then adjusted to the 35% minimum required by law.
Since natural vanilla is very expensive, imitation vanilla is often used to mix with or completely replace natural vanilla. Imitation vanilla was produced from eugenol, which was itself produced by oil of clove, but now it is made from sulfite waste liquors from the paper industry.
Vanilla extract from Mexico should be used with caution, as health standards in Mexico allow vanilla extract to be cut with certain chemicals that contain carcinogens. Most reputable dealers, however, make vanilla using only FDA-approved additives.