- How long does an unopened package of active dry yeast last? The precise answer depends to a large extent on storage conditions -to maximize the shelf life of unopened active dry yeast store in a cool, dry area.
Properly stored, an unopened package of active dry yeast will generally stay at best quality for about 12 to 18 months.
Is unopened active dry yeast safe to use after the "expiration" date on the package? Yes, provided it is properly stored and the package is undamaged - commercially packaged active dry yeast will typically carry a " Best By," "Best if Used By," "Best Before", or "Best When Used By" date but this is not a safety date, it is the manufacturer's estimate of how long the active dry yeast will remain at peak quality.
Storage time shown is for best quality only - after that, the active dry yeast's texture, color or flavor may change, but in most cases, it will still be safe to consume if it has been stored properly, the package is undamaged, and there are no signs of spoilage (see below).
How can you tell if active dry yeast is still good to use? To test whether yeast is still potent enough to be effective: Add 1 teaspoon sugar to 1/4 cup warm water and stir in 1 envelope (or 2 1/4 teaspoons) of yeast; let stand 10 minutes — if the yeast foams up to the 1/2 cup mark, it will still be effective.
Sources: For details about data sources used for food storage information, please click here