How to know when white mushrooms have gone bad

Updated April 17, 2017

Mushrooms are an edible fungus with a rich, earthy flavour. There are several varieties of wild and cultivated mushrooms that you can use fresh or dried to prepare tasty and nutritious meals. Exotic mushrooms, such as maitake and shiitake can be found dried rather than fresh, unlike white mushrooms such as button mushrooms and cup mushrooms, which are widely available fresh. Fresh white mushrooms have a short shelf-life and degrade easily in the presence of light, heat and air. Carefully inspect white mushrooms when purchasing and before cooking, to determine whether they are safe for consumption.

Examine the colour and texture of the white mushrooms. Mushrooms that are old and spoiled due to dehydration have a dried, greyish tinge and are shrivelled. White mushrooms should be unblemished with a smooth texture and bright white colour.

Check the cap of white button mushrooms and cup mushrooms. Turn the mushrooms over to examine the caps. Open caps indicate that the mushrooms are old, whereas closed caps are a sign that the mushrooms are young and tender. Mushroom caps open up as the mushrooms age.

Observe the surface of the white mushrooms. If you notice mould and a thin layer of slime covering the mushrooms, they are spoiled.


Store mushrooms in a paper bag in the refrigerator, at a temperature of around 4.44 degrees C. Use the mushrooms within three days of purchase or by the use-by date on the packaging.


Do not keep mushrooms in plastic bags to prevent them from spoilage due to excess moisture created in the bags.

Things You'll Need

  • Fresh white mushroom
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