How To Tell If Mushrooms Are Bad: The Complete Guide

No one wants to get sick from eating the food they prepared. With how prevalent E. coli and salmonella are, it’s important to know how to tell if mushrooms are bad so you can stay safe. I’ll explain how to spot the signs of a spoiled mushroom, how long you should store them in the fridge, and what you need for a clean space when cooking them.

Your mushrooms have gone bad if:

  • They have brown or black discolorations on them
  • They smell strong and sour
  • There is fuzzy growth
  • There is a clear slimy film on the mushroom surface
  • The mushrooms have become shriveled, has wrinkles, or has dried out
  • They have been in your fridge for too long, more than 2 weeks

Let’s take a deeper look into each of these signs of rot so you can tell what’s happening to your store bought mushrooms.

What Does A Bad Mushroom Look Like?

rotten mushrooms

Dark Spots

Dark marks and discolorations on mushrooms happen when the mushroom has been exposed to air for too long. This air exposure causes the mushrooms to oxidize, causing these discolorations. When you see these dark spots, your fresh mushrooms are past their prime.

Slimy Film on the Mushroom Surface

Mushrooms can develop a slimy film on them when they are old and past their prime. This film is a result of the decomposition process and is common in fungi. The mushroom is beginning to break down its own natural nutrients which can cause this film. If you see this slimy sign, toss them right away.

A Strong Sour Smell

Mushrooms naturally have an earthy smell that is noticeable, but not unpleasant. If you notice a strong, unpleasant smell on your mushrooms then they are not good to eat anymore. A bad mushroom may smell like chemicals, mold, or decay. It may also have a sour smell, a byproduct of the mushroom breaking down due to fermentation. This is a sign that it’s time to throw them in the trash.

Too Long In The Refrigerator

If your mushrooms have been in the fridge too long, they will eventually go bad. Mushrooms last for a shelf life of 7 days to two weeks depending on whether or not they are stored properly. 10 days is a good average as a rule of thumb. However, they can start to decompose within a matter of days if your store bought batch was older. In this case, it’s important to keep looking for signs of bad mushrooms by following the indicators above.

Can You Get Sick From Eating Old Mushrooms?

man eating a mushroom

You may experience gastric issues and stomach pain if you eat old mushrooms. However, it is highly uncommon to catch a major case of food poisoning from old mushrooms. Cooked mushrooms have fewer bacteria in them and are therefore safer to eat.

Store-bought mushrooms generally meet the standards for how long they are safe to eat due to their expiration date and shelf life. However, they can go bad faster than you might expect if not handled properly.

If raw mushrooms have gone bad and you don’t plan to cook them, they present a higher risk of food poisoning, since they won’t be cooked. Make sure to eat your raw mushrooms by the sell date and throw them away the second they start going bad.

Certain people may be more susceptible to food poisoning from old mushrooms, including pregnant women and people with a compromised immune system.

Will Cooking Mushrooms Kill Bacteria?

cooking mushrooms

Cooking mushrooms will kill any bacteria on the surface of your mushroom and in the food itself, but it is important to know how long you should cook them as well.

There are many factors that go into how much time a particular type of mushroom needs to cook, including how big they are cut up or sliced, how much water is in the pan, how much oil or butter is being used for cooking, how hot your stovetop is set to, and how brown you want them.

It’s best to follow a recipe when it comes time to cooked mushrooms as this ensures that they are cooked through properly and also prevents any overcooking or undercooking of the mushroom.

If it looks like your mushrooms have gone bad to a slight extent but you still want to eat them, make sure you add a bit of extra cooking time to the mushrooms to make sure you kill all of the bacteria.

Slow cooking mushrooms is a great way to tell if your mushrooms are fully free of any harmful bacteria. While we often think of heat as the primary indicator of doneness, the length of time also helps to get rid of pathogens. You can use a crockpot or sous vide to make sure they are cooked for long enough.

Should Fresh Mushrooms be Washed?

washing mushrooms

You don’t necessarily need to wash your mushrooms before eating them. You should wash them only if they are covered in dirt or have been sitting on a dirty surface. This is because washing your mushrooms can actually expose you to more bacteria than would be present otherwise.

When the water comes into contact with your mushrooms, it can spread bacteria on the surface of your mushroom and into other areas.

It’s best to wash mushrooms only if they are visibly dirty, like after a day at the farmer’s market where you might not have been able to see how clean that particular pile was. Otherwise, it is better just to use a damp paper towel or cloth when cleaning them.

Focus on storage in a proper container in your fridge instead of washing your mushrooms. This will help extend their shelf life. 

How Can I Choose Fresh Mushrooms At The Store?

grocery shopping for mushrooms

How long do mushrooms last in the grocery store? Their shelf life depends on several factors.

You can tell how fresh your mushrooms are by how they are packaged. Mushrooms that are sold in a tray or container should be fresher than those sold loose. If the caps on the mushroom look dry and shriveled, then they have probably been sitting around for a while and aren’t as good of quality.

Mushrooms also need to be chosen carefully if you want to eat them raw. If you’re cooking mushrooms, then this is less of an issue, but there are still things to consider when you go shopping.

It is best to buy mushrooms that have tight attachment points and close gaps between the gills. These mushrooms will be less prone to contamination from other foods and any bacteria on the surface will be contained and unable to spread.

Buying whole mushrooms as opposed to sliced mushrooms will also ensure that your mushrooms are fresher. The less processing that has occurred, the longer you’ll want to keep them in your refrigerator.

How Do You Keep Mushrooms Fresh Longer?

You can store your fresh mushrooms for up to two weeks by wrapping them loosely in a paper towel before storing them in a plastic bag. This protects the mushrooms from exposure to air, which can cause them to go bad quicker.

Store your clean and dry mushrooms between 34-40 degrees Fahrenheit for up to two weeks. Keep them away from any meats or other food products that have been sitting out at room temperature for more than four hours.

Another tip for helping your mushrooms last longer is to not wash them until you’re ready to cook them. Mushrooms are porous and can easily absorb water, which will cause the mushrooms to rot quickly. Instead, store the mushrooms unwashed in a paper towel.

Can I Freeze Mushrooms?

frozen mushrooms

It can be challenging to put raw mushrooms in the freezer and may actually reduce their shelf life. Mushrooms are an organic product and they will spoil and break down after a week or less of freezing.

If you do freeze your fresh mushrooms, they will begin to rot and spoil after a week or less. They will look like how a mushroom would look if you had forgotten to cook it and left the pan out overnight. The texture will be slimy and the mushrooms will have a sour taste, and the mushrooms have gone bad.

One way around this is by using partially cooked mushrooms in the freezing process. Another is to freeze them at a low temperature for a long period of time. This will minimize the slimy texture and the sour taste may alter the overall texture. Make sure you have an appropriate storage container that doesn’t let oxygen in and can prevent freezer burn. A big will work great to protect the food.

While there are a few exceptions to this rule, (for example, Shiitake mushrooms), the vast majority of mushrooms are impervious to freezing, so it’s best not to try unless you are feeling secure in how to tell if mushrooms are bad.

How To Freeze Your Mushrooms

Are Wild Mushrooms Fresher Than Store Mushrooms?

foraged mushrooms

How long do freshly picked mushrooms last? Wild mushrooms, whether purchased from a farmers market or hang foraged, are as fresh as they come.

The mushrooms will be extremely delicate and should not be stored for long periods of time unless you have a controlled environment to keep them in, like an unheated garage or basement during the winter months. They are best used within two days of purchase or picking so that they don’t spoil if there is any moisture.

Wild mushrooms could be kept longer by cooking them before storing them in the fridge. Removing some of the water from the mushroom will also help it stay fresh longer as well as keeping it wrapped in a paper towel.

Tips for Proper Storage of Mushrooms.

mushrooms in a fridge
  • Make sure they’re stored properly in your refrigerator. Keep them away from strong-smelling foods like onions and garlic; store accordingly so the aromas don’t get mixed up. You’ll also want to keep them far away from meats and cheeses.
  • They prefer breathable containers. Mushrooms will stay fresh for longer when stored in an open container rather than a sealed one. You’ll need to find a balance between providing them with some airflow while being careful to not dry them out. A paper bag or paper towels do a great job at this.
  • Store mushrooms in their original container. The less they are handled, the less they will be exposed to bacteria. This will help make sure they don’t get slimy too quickly.
  • Make sure to replace the packaging film tightly. When you use a couple of your mushrooms and put the rest of the packaging back into the fridge, make sure you secure the saran wrap on it tightly. This will improve the shelf life.
  • Once cooked, keep them covered and away from heat sources such as light bulbs, stoves or other foods that produce a lot of steam. You want the mushrooms to stay fresh for as long as possible so take care not to expose them unnecessarily.

Final Thoughts

mushrooms on kitchen table

How long do mushrooms last? That depends on if you know how to tell if mushrooms are bad when grabbing them at the grocery store and how you stored them once they made it home. Even though mushrooms last 7 days or more, it’s best to eat your whole mushrooms within 3 days of purchasing them if possible.

Remember that proper storage could prevent your food from becoming spoiled, dark, full of wrinkles, all signs that your mushrooms are bad. Their shelf life is determined by these practices. Mushrooms last surprisingly long when you take good care of them after coming home from the grocery store. Let me know your tips and tricks for preserving your fungi in the comments below!

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