How to Tell if Mushrooms Are Bad? 6 Signs to Watch For

pack of white mushrooms

Mushrooms are fungi that typically come covered in a little dirt, so it can be difficult to tell if they’re bad or they’re just, well, fungusy. If you’re wondering how to tell if mushrooms are bad, their texture is the first giveaway. Mushrooms should be firm and plump, so if they exhibit any of the signs we outline below, your mushrooms may be destined for the trash.

The good news is that mushrooms last at least a week in the fridge.

How Long Do Mushrooms Last in the Fridge?

  • Sliced mushrooms: 5-7 days
  • Whole mushrooms: 7-10 days

Signs Mushrooms Are Bad

inspecting mushroom with magnifying glass

If your mushrooms smell or feel suspicious, think twice about using them. Sliced mushrooms will spoil more quickly than whole mushrooms, so consider buying mushrooms whole and slicing them yourself. (They’re usually cheaper whole, too!)

Here are the tell-tale signs that your mushrooms are bad or about to go bad.

1. They’re Slimy

This is the #1 sign that tells me my mushrooms are on the verge. Slime means that bacteria is starting to grow on your mushrooms. 

If they’re barely slimy, meaning they primarily feel moist to the touch with a slight film, I’ll rinse them off and cook them. However, if they’re slippery to the touch, avoid eating them.

Remember, everyone’s tolerance is different, so if you’re unsure that probably means your mushrooms are past their prime.

2. They Have an Unpleasant Smell

Fresh mushrooms have a very mild, almost non-existent, smell.

Bad mushrooms are more pungent. They can have a musky, sour odor or smell slightly fishy. If your mushrooms are giving off a scent that makes you wrinkle your nose, they’ve gone bad.

3. They’re Wrinkled

Mushrooms are full of moisture. When they start to dehydrate, they’re on their last legs. If your mushrooms only have a few small wrinkles, they’re probably still okay to eat. However, if they’re shriveled, they’ve passed their expiration date.

4. They’ve Darkened

Over time, mushrooms can develop dark spots or the whole shroom can darken. This is most apparent on white or light colored mushrooms. This typically happens in tandem with the mushrooms softening. If the mushrooms are significantly darker than when you bought them, they’ve likely gone bad.

5. They’re Spongey

Mushrooms should be firm. If you pick them up and they feel soft, squishy, or spongey, it’s time to toss them. At this stage, it almost feels like they’re starting to become hollow inside.

6. They’re Moldy

mold growing on mushrooms

This is an obvious sign that any food is going bad. If you see spots of white or green fuzzy mold, your mushrooms are past their prime. Since mushrooms are moist, it’s essential to store them properly to reduce the risk of mold. More on that below.

What Different Types of Mushrooms Should Look Like

There are so many different types of mushrooms, it can be hard to remember the difference and what each type is supposed to look like. These are some of our favorites:

  • White: Also known as button mushrooms, these immature varieties are found in most grocery stores. They have a mild flavor and can be used in everything from pizza toppings to omelets. 
  • Baby bella: Also known as cremini, these brown mushrooms are small and firm. They are the juvenile version of portobello mushrooms.
  • Portobello: These have a savory, earthy flavor. They are known for their large caps and are sometimes used as a meat substitute. They have a chewier texture than other mushrooms.
  • Shiitake: Shiitake mushrooms have brown caps and lighter stems. They have a rich, umami flavor.

While all these mushrooms will show similar signs when they’re going bad, it’s important to understand how each appears when it’s fresh so you can spot when something is off.

How to Store Mushrooms

Over time, mushrooms release moisture. It’s best to store them in something that absorbs this moisture. Our preference is a paper bag lined with paper towels. Take the mushrooms from the store-bought container, place them directly in the bag with paper towels (no washing!), and store them in your fridge. It’s best to avoid high-humidity crisper drawers.

What to Use Mushrooms For

You can eat mushrooms fresh, sauteed, roasted, or grilled. These are some of our favorite dishes to add mushrooms to:

One of my favorite breakfasts is over medium eggs and rice with soy sauce. You can saute mushrooms in sesame oil and pile them on top for a savory and fulfilling breakfast.

How to Freeze Mushrooms

If you’re worried that your mushrooms will go bad before you can use them, you can freeze them. Here’s how:

  1. Clean the mushrooms thoroughly. 
  2. Cut them if you want to freeze sliced mushrooms. Otherwise leave them whole.
  3. Cook them.
    • Option 1 Saute: Using oil or butter, saute your mushrooms for a few minutes until they are soft.
    • Option 2 Steam: Add a teaspoon of lemon juice to your water. Add mushrooms to a steamer basket and steam for a few minutes until they’re soft.
  4. Spread mushrooms out on a cookie sheet and flash freeze them. They should be frozen solid.
  5. Transfer to a freezer-safe container and store for up to 3 months.

When you’re ready to use your mushrooms, add them to your recipe!

Mushrooms are a healthy and delicious addition to any dish. Did you know that one cup of sliced mushrooms is only 15 calories? Plus, mushrooms are rich in B vitamins, antioxidants, and potassium. Just remember, mushrooms typically last 7-10 days and if you notice any signs of mushrooms going bad like a smelly odor or slimy texture, think twice before using them.