The 2 year shelf life date is given by the fda and other agencies to ensure that consumers are using viable products. Many studies, including ones for pharmaceuticals, have shown that the 2 year date is inaccurate and fairly randomly assigned.
Keep extracts out of the fridge.
Refrigerating flavor concentrates
- speeds up the natural separation of the flavor from the liquid base
- allows unwanted condensation to form
- temperature fluctuations lessen the shelf life (unless you're going to mix in the fridge)
To extend the shelf life
- make sure lids are on securely
- keep in a cool, dark place away from heat, moisture (like a fridge), and sunlight
If you're keeping them in the kitchen, avoid cupboards near the stove, dishwasher, fridge, or even shelves by windows...which means the kitchen isn't the best place to store them. You want to minimize temperature variations.
If you keep them in an ideal location, they should last 2 years to
indefinitely.
After awhile, they will lose flavor potency, but they do not go bad.
Flavored Oil are the exception. These can and should be refrigerated. Bacteria seems to grow in oils in room-temperature air. However, they should not be stored in a freezer.