Wood pulp, coal tar, and cow poop are all potentially on the table
W e don't mean to alarm you, but you probably have a taste for wood pulp waste. You've mmmmm-ed and ohhhhh-ed over it for years in your favorite baked goods, sweet breakfast dishes, and frozen treats without even knowing it, but yeah. It's fine, it's just lignin—or wood polymer—waste from the process of making paper, and it's one of the many stand-ins for the flavor of vanilla in imitation vanilla extract. Minus seeing a label, you might be hard-pressed to smell or taste the difference between pure vanilla extract and imitation vanilla extract, especially in dishes where it's just an accent note, but it never hurts to know exactly what you're stuffing in your cakehole.
Pure vanilla extract is obviously excellent, or else it wouldn't have spawned so many imitators. But it can also be incredibly pricey, and contains alcohol—a no-no for plenty of bakers and eaters for various reasons. That's where imitation vanilla comes into play. Pure vanilla extract is made by steeping vanilla beans in ethyl alcohol and water. The beans are painstakingly grown, hand-harvested, and shipped from just a few countries—hence the high cost.
Imitation vanilla, however, is made from synthetic vanillin, which is the compound that naturally occurs in vanilla beans and gives it that distinctive flavor. This synthetic vanillin can come from the previously mentioned wood pulp waste (though that's recently fallen out of favor) or coal tar, cow poop, secretions from a beaver's castor glands (located conveniently near its anus), clove oil, pine bark, or fermented bran.
Guaiacol, which is derived from wood creosote or the guaiacum flower might also be pulling faux-vanilla duty, but due to some FDA labeling wackiness, most manner of these flavors might be labeled as "natural" since they were technically derived from edible sources. (Sorry, cow poop—you don't make the cut. Weirdly, the beaver excretions do, but due to the highly labor-intensive and frankly nasty collection process—for both parties—castoreum is used extremely infrequently and the average consumer will likely never encounter it.)
On the flip side, real vanilla extract (which can also be labeled as "extract of vanilla") is the only flavor that's regulated by federal law. Per the official FDA code: "In vanilla extract the content of ethyl alcohol is not less than 35 percent by volume and the content of vanilla constituent, as defined in 169.3(c), is not less than one unit per gallon." If the extract is made from vanilla oleoresin, concentrated vanilla extract, or concentrated vanilla flavoring, the label must say "made from" or "made in part from" those particular ingredients.
In 2009, Cook's Illustrated conducted an intensive taste test to see if subjects could tell the difference between pure vanilla extract and imitation vanilla. The results varied, depending on how the vanilla was deployed—in a cake, pudding, cold dessert, or solo—but the upshot was that while pure vanilla extract is ideal, there's not a huge drop-off in quality if you opt for a well-made imitation.
Got a few months to spare? It's incredibly easy to make your own vanilla extract at home using vanilla beans and high-proof alcohol. Just flatten and split the vanilla beans, put them in a jar, pour alcohol over them, and open three months later—no cow poop or beaver butts needed.