Some cooks prefer to buy certain spices whole, black peppercorns being the best known example. Cumin, fennel, coriander, and nutmeg are some others. It is said that whole spices do not expire - or do they?
What Happens to Whole Spices?
Whole dried spices do not literally "expire," but they do slowly fade away – that is, lose potency and flavor. It's a slow process, but according to McCormick (the spice merchants) and other sources, after 2-3 years you can expect noticeable loss of flavor in your whole spices. Because this loss is gradual you might not notice it. This is why some folks date their spice bottles upon purchase. Of course, pre-ground spices lose flavor a lot faster, in 1-2 years perhaps.
Why Do Spices Fade?
The flavor elements in spices comprise aromatic oils. Exposure to the oxygen in air degrades these oils and the flavor is lost. In whole spices these oils are better protected from the air and the flavor therefore lasts longer compared to ground spices. Note that this is not any kind of spoilage, and old spices are perfectly safe to eat even if they may be tasteless.
Spice Storage Recommendations
Spices should be stored in airtight containers, away from heat, light, and humidity. Definitely not above the stove! If you have large quantities of a spice, freezer storage will further extend life. Again tightly sealed, keeping a small amount out for daily use and dipping into your freezer store as needed.
Here's another spice-related myth that doesn't hold water, this one about peppercorns.
