When you pay the high price tag for pure vanilla extract, you want to make sure it lasts. Proper storage means it will keep pretty much indefinitely. Imitation vanilla provides a cheap substitute, but if you use it primarily in baked goods, it's hard to discern the difference. Storage and shelf-life are similar despite the quality and price differences.
Pure vanilla extract benefits from storage in an airtight container away from direct sunlight. A cool, dry place, such as a pantry, works best. Refrigeration or freezing of the extract separates the vanilla from the liquid in which it's suspended and can compromise quality. Imitation vanilla should also be stored in a cool, dry place, and not refrigerated or frozen. Keep both out of cupboards near the stove or oven.
Pure vanilla extract can actually improve with age. The flavor deepens as it gets older, with many bottles improving after three years of being stored properly. Imitation vanilla will last just two to four years when properly stored.
Signs of Spoiling
If your bottle of pure extract begins to develop sediment at the bottom or looks cloudy, it may just need a good shake. Vanilla extract with sediment is probably past its prime, though, and may not have as much flavor. If you aren't sure how long you've had the extract, and it emits a sour or unpleasant odor, you're probably wise to ditch it and start with a fresh bottle.
Vanilla extract, by law, must contain 35 percent alcohol. The alcohol is the primary reason pure extract has such a long shelf life. Imitation vanilla usually doesn't contain alcohol. Homemade vanilla extract, made by infusing vanilla beans in liquor, also improves with age. Allow it to steep for at least one month -- or several months for more intense flavor.