Can You Safely Eat Mushrooms That Have Become Slimy?

It's meal prep time, and you find a package of mushrooms in your fridge that would be perfect for your omelet and side dish. However, you realize the package has been there for several days. Upon inspection, the mushrooms seem fine except for a slight glossy sheen on their surface. The question arises: are these slimy mushrooms still safe to eat?

How Long Can Mushrooms Stay Fresh in the Fridge?

Fresh mushrooms typically stay good for 1 to 3 days at room temperature. If you refrigerate them right after purchase, they can remain fresh for an additional 3 to 7 days.

The USDA Foodkeeper App suggests that you can freeze fresh mushrooms for 10 to 12 months. However, since mushrooms are high in water, thawed mushrooms may become soft and mushy.

The shelf life of mushrooms also depends on several factors, including:

• Their size: Bigger mushrooms like cremini and portobello last longer than smaller mushrooms
• Their form: Sliced mushrooms have a shorter shelf life than whole due to the former's inner contents being exposed to air
• How they are stored: Mushrooms last longer when stored in a paper bag instead of in a plastic bag in the crisp drawer of the fridge as the former allows for airflow and excess moisture absorbed.
  

Why Do Mushrooms Become Slimy?

The way mushrooms are stored plays a significant role in how long they remain fresh. Even after being harvested, mushrooms are still living organisms.

Mushrooms lack the protective skin that fruits like apples and pears have, which helps guard against drying out and rotting. When stored in plastic or paper packaging, the moisture trapped inside creates an ideal environment for bacteria and mold to grow. The glossy appearance on mushrooms is therefore a clear sign of spoilage.

Can Slimy Mushrooms Be Eaten?

Even if you're tempted to salvage them for your favorite risotto recipe, it's safest to avoid eating slimy mushrooms, as the slime indicates the mushrooms have begun to spoil.

While eating a few slimy mushrooms might not make you sick, consuming food contaminated with harmful bacteria could cause illness. After harvesting, mushrooms can be exposed to pathogens like Listeria monocytogenes, which, according to the CDC, is commonly found in foods like soft cheeses, deli meats, and unpasteurized dairy products.

Mushrooms are typically grown in pasteurized manure compost, which helps limit the growth of Listeria. However, they can still become contaminated with harmful bacteria during post-harvest processing when they're sorted and packaged for retail distribution.

How to Determine If Mushrooms Have Spoiled

Before deciding whether to consume slimy mushrooms, carefully inspect each one. Are they discolored, shriveled, or do the gills underneath appear wet and collapsed?

If the mushrooms were stored in their original packaging rather than a paper bag, check the bottom of the package. As mushrooms begin to spoil, their cell walls break down, releasing moisture.

Next, give the mushrooms a sniff. Fresh mushrooms have a light, earthy smell. If they emit a strong or unpleasant odor, even with only a bit of slime, it's best to discard them.

What About Washing and Cooking Spoiled Mushrooms?

When handling mushrooms, whether they're slimy or not, it's best to avoid washing them until you're ready to cook. Be sure to wash your hands before and after handling the mushrooms, and always use a clean cutting board.

Though it's not ideal, if you absolutely need to use your slimy mushrooms, you can rinse off the slime and cook them. Taste test them to check if they still have their characteristic umami flavor. If they taste bitter or unpleasant, it's better to throw them out.

Since mushrooms can carry harmful microorganisms, it's safest to cook them before eating. If you're adding them to a mixed dish, ensure the internal temperature reaches 165°F.