Vanilla extract is around 35 percent ethyl alcohol, which has a harsh, biting flavor.
Whiskeys and other distilled beverages contain even more alcohol, of course (usually 40 percent), but they are lovingly produced by time-honored flavoring and aging processes that soften the harshness.
“Pure vanilla extract,” in order to be labeled as such, must be extracted from real vanilla beans.
But the chemical that gives the beans most of their great flavor and aroma is vanillin, and chemists can make vanillin a lot more cheaply than the vanilla plant (an orchid) can. Synthetic vanillin is used commercially to flavor baked goods, candies, ice creams, and such. It’s identical to the natural chemical, and is the main ingredient in imitation vanilla flavoring.
Real vanilla extract is so much more complex than just plain vanillin, however, that it doesn’t pay to buy the imitation stuff, especially since you use so little of it and it keeps forever. More than 130 distinct chemical compounds have been identified in true vanilla extract.
Even better for some applications is a whole vanilla bean, obtainable for a few dollars in an airtight glass or plastic test tube. The bean should have a flexible, leathery texture, rather then being dried out and hard.
The vanilla “bean” is not a bean, by the way; it’s a pod. Beans are seeds, whereas pods are fruits that contain seeds. The vanilla flavor and aroma are mostly concentrated in the pod’s seeds and especially in the oily liquid that surrounds them, so for the most intense flavor as a recipe ingredient, slit the pod lengthwise with a sharp knife and use the seeds, scraping them out with the back of the knife blade.
The pods are also aromatic and flavorful, however, and should not be discarded. Bury them in granulated sugar in a tightly sealed jar for a few weeks, shaking the jar periodically.
The sugar becomes infused with the flavor of vanilla and is great in coffee or for flavoring baked goods.