Do Boxed Mashed Potatoes Ever Really Go Bad?

With a wide range of uses that go beyond a humble side dish, boxed instant mashed potatoes are a pantry staple we always like to have on hand. But as with any product with a long expiry date, it can be easy to forget just how long it's been sitting there. So with that in mind, do instant mashed go bad in the truest sense?

Depending on the brand, the shelf life of unopened boxes of mashed potatoes runs between one to two years. Even the best-by date on the package will represent when it can be eaten to enjoy the best quality and flavor, and not when it is safe to eat.

But before you dive into a packet of expired mashed potatoes, you should know that they can turn bad when not stored correctly. Although the dry environment generally inhibits the growth of bacteria, any breakdown in the packaging or changes in temperature can allow moisture to enter which can lead to mold and the growth of bacteria. Bacteria can lead to food poisoning, while molds may produce mycotoxins that can cause allergic reactions or more serious health concerns.

While the package remains unopened and intact, your instant mashed potatoes should still be good, even well beyond the best-before date. But to keep them at their freshest it's important that you keep them in a cool, dry place like a cupboard. Exposing the box to sunlight or temperature changes can speed up the spoilage.

Once opened, it's essential that your dried potatoes stay dry. If the packaging is not resealable, then transfer the unused portion to a good airtight bag, and consider adding a food-safe desiccant from a brand like Vbeijll if you live in a humid area. These should remain safe to eat for two to three months, but look out for any signs of spoilage. If you notice a change in color, smell, or visible signs of mold, they should be discarded. Clumping of the powdered potato means that it has taken on moisture, so check carefully for mold before cooking.

In theory, freezing your opened boxes of mashed potatoes will extend their shelf life, but you're running the risk of introducing moisture. Unless you have complete confidence in the seal of your container and the temperature control of your freezer, you're probably better off finding ways to use up your instant potatoes.