How To Tell If Store-Bought Mushrooms Have Gone Bad

With proper storage, raw mushrooms can last around four to seven days, depending on the species. If your mushrooms are past the sell-by date on their packaging, or if you've foraged them yourself, there are a few things you'll want to check before cooking with them. For starters, if you notice any nasty smells coming from the container, that's your nose signaling a warning not to eat them. As they say, "The nose knows."

You should not ingest mushrooms with fuzzy or discolored spots, as that's a sign of mold. When it comes to growing mushrooms at home or foraging, you might notice networks of thin, fibrous white mycelium — that's perfectly normal, though you will not typically see mycelium on any mushrooms from the grocery store. Cottony black, blue, and grey mold spores are dangerous, and they'll contaminate the whole mushroom, even if you were to cut pieces off.

Slimy and soggy mushrooms don't belong in your food. It's a sign of decomposition, and nature is telling you it's time to let go. The opposite is true as well; dry, shriveled-up mushrooms with wrinkly caps are too old to tango. A good rule of thumb is that if the mushrooms have changed in appearance from when they were freshly plucked and sold, it's not a positive transformation — they're just rotten.

A common mushroom mishap is to store them in plastic. Unfortunately, plastic traps moisture and suffocates mushrooms with high water content. They need room to breathe. One of the best methods for storing mushrooms is to wrap them in a paper towel and put them in a brown paper bag in the refrigerator. Do not wash or cut them until you're about to cook with them, as both of these actions will speed up their expiration. You can also try drying mushrooms at home to extend their shelf life.

When the time comes to dispose of any mushrooms you weren't able to cook, there's a more sustainable way to banish them than simply tossing them into the garbage can. Composting allows you to get rid of organic scraps and create a formation for growing food at home. Even moldy produce like mushrooms is generally safe to toss into the mix. We might not like rotting food, but earthworms and fungi are happy to take the leftovers. It's a win-win situation.