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How to Tell When Mushrooms Are Bad: 5 Tell-Tale Signs

Kathryn studies and writes about health, nutrition, and food safety.

Are your fungi fresh or foul? Eat safe, and learn the signs of spoiled mushrooms.

Are your fungi fresh or foul? Eat safe, and learn the signs of spoiled mushrooms.

Nervous About Your Mushrooms?

Mushrooms are an iffy food for a lot of people. After all, they're one of the only things we eat that isn't a plant or an animal. Over the years, however, more and more people have become interested in cooking and consuming mushrooms. They're healthy and low on calories, and their unique textures and flavors incorporate well into a wide variety of dishes.

Some people are hesitant to try them due to the fact that certain species are inedible, poisonous, or have hallucinogenic effects. You might think that if your store-bought mushrooms go bad, you'll end up going on a bad trip. Luckily, this is not so.

Bad mushrooms can, however, make you very sick. The risk of this happening is low if the mushrooms you eat are store-bought or farm-fresh. They pose even less risk if you eat them cooked. Nevertheless, it's still a good idea to take steps to avoid eating spoiled or rotten food. You don't want to take any chances.

This article discusses tell-tale signs to look for to determine whether your mushrooms have turned and provides tips on how to properly store them to prevent (or at least delay) spoilage.

How Long Do Mushrooms Last in the Fridge?

Most chefs and experts agree that, if stored properly, raw mushrooms can last up to two weeks in the fridge before spoiling. Some mushroom species may last longer, while others may spoil more quickly. Other factors like fridge temperature and moisture levels can also affect the longevity of mushrooms' freshness.

If your mushrooms have dark spots on them, they've gone bad. Make sure you throw them out!

If your mushrooms have dark spots on them, they've gone bad. Make sure you throw them out!

How to Tell if Your Mushrooms Have Gone Bad

Here are some obvious and not-so-obvious signs that your mushrooms need to go in the trash. Use your best judgment, but err on the side of caution when deciding whether to keep, cook, or toss your fungi.

  1. They're slimy. The number one rule of thumb when it comes to detecting freshness is that when mushrooms are slimy, they're no longer fit for eating. Sliminess often occurs on mushrooms that have been sitting in the fridge for too long. While they aren't definitively dangerous at this point, it's still a good common kitchen practice to toss them.
  2. They have wrinkles. Sometimes, older mushrooms don't get slimy and instead dry out and get wrinkles. While it's okay to dry out your mushrooms a little bit (since they are fairly moist vegetables anyway), you don't want your mushrooms too wrinkly. If they look pretty shriveled, it's a safer bet to toss them than consume them.
  3. They're becoming darker or have dark spots. Dark spots are a sign that your fungi are starting to go bad. The best thing that you can do is to keep an eye on your mushrooms throughout the entire time they're in the fridge. If you notice them getting darker or developing dark spots, it's time to use them or lose them.
  4. They've been around for two weeks or more. The general consensus in terms of shelf-life/storage time with mushrooms is that about two weeks in the fridge is the outer limit. Of course, you should use your common sense and best judgment. If it's been just over two weeks, but they still look, smell, and feel fine, they're probably safe to eat.
  5. They emit an odor. Your mushrooms shouldn't have a noticeable or strong odor. If you can smell them, they've gone bad. Of course, if you're sticking your nose right up to them, you'll notice a mushroom scent, but it should be light and subtle. If you pick up the bag, open it, and have to turn your head, then you've got bad mushrooms. Get rid of them!

Signs of Spoiled/Rotten Mushrooms

Use your best judgment. Sniff, eyeball, and poke at your mushrooms to determine whether they're still fresh or not. Use this cheat sheet if you need help, but always err on the side of caution.

They smell bad

They're wrinkly

They're getting darker

They're slimy

They're older than two weeks

They've developed dark spots

An ideal way to store mushrooms is to simply keep them in their original sealed container until you're ready to eat them.

An ideal way to store mushrooms is to simply keep them in their original sealed container until you're ready to eat them.

How to Properly Store Mushrooms

How can you properly store mushrooms to optimize their shelf life? Here are a few storage tips to help you get the most out of your fungi before they spoil.

  • Let them breathe. Store mushrooms in a way that allows them some air without drying them out too much. Keeping them in a paper bag with the top loosely rolled up inside the refrigerator is a popular storage method.
  • Use plastic bags and paper towels. Another way to keep mushrooms relatively fresh is to store them in plastic bags lined with paper towels to help capture moisture. Make sure you change the towels regularly if you don't plan to use your mushrooms right away. It's a good idea to experiment with including them in a variety of dishes so that you use them up before they go bad!
  • Keep them in their sealed wrap. One of the most effective storage techniques is to simply keep them in the sealed containers/bags that they come in. If they are packaged in a cardboard tub wrapped with plastic, there's no need to transfer them to an alternate container when you bring them home. Make sure you don't open or tamper with them until you're ready to use them.
  • Freeze them. It is possible to freeze mushrooms for later use. Because mushrooms retain so much water, however, it's much more difficult to freeze them when raw. If you're going to do so, make sure you freeze them on parchment paper and then quickly transfer them to an airtight bag with as much of the air pressed out as possible. The best way to freeze them is to cook them first, then pack them into airtight containers or freezer bags (use whichever holds less air when sealed).

Remember, being afraid that your mushrooms are going to go bad isn't a good reason not to eat them. Use some common sense, look out for the obvious signs, and enjoy the texture and nutrition that these flavorful fungi can add to your recipes!