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College of Food, Agricultural, and Environmental Sciences


Chow Line: When good mushrooms go bad (for 1/28/07)

January 19, 2007

I enjoyed your recent article on mushrooms. My question is, what are the signs that mushrooms have spoiled?

That almost sounds like part of a stand-up comedian's routine: How do you tell when a fungus has gone bad? But you can be on the lookout for a number of clues -- and it's important to do so. Spoiled mushrooms can make you ill -- even those that aren't poisonous to begin with.

First, mushrooms should have a pleasant, earthy aroma. If you get a whiff of an ammonia smell, it's time to toss them. Mushrooms should be dry -- not dried out and withered, and certainly not slimy. And fresh button mushrooms should be light in color -- they darken as they age.

Different authorities will give you different recommendations about storing mushrooms when you bring them home from the store. All say to store them in the refrigerator, but some say to keep them in their original container. Some say to remove the plastic wrap from the container. And still others say to remove the mushrooms from the container and put them in a brown paper bag. The idea is to prevent moisture condensation, which could promote spoilage, from building up. In addition, be sure to store mushrooms on a regular shelf in the refrigerator, not in a produce drawer that has higher humidity than other parts of the refrigerator. By keeping moisture low, they should keep in the refrigerator for about a week.

Still, it's always a good idea to use mushrooms soon after purchasing them. This will, of course, prevent them from going bad. But in addition, mushrooms tend to absorb aromas and flavors from surrounding foods -- that's one of their best attributes when using them in stews, casseroles, sauces and other mixed dishes. But they also may do so if they sit in your refrigerator too long, waiting to be used.

Before using whole mushrooms, it's a good idea to clean them first. The Mushroom Council ( recommends gently wiping mushrooms with a damp cloth or soft brush, or rinsing in cold water and patting dry with paper towels. This should be done immediately before using them.

Mushrooms are low in calories and are considered good sources of potassium, folate, niacin, fiber, copper and selenium. For nutrient information on different types of mushrooms, see the U.S. Department of Agriculture's National Nutrient Database at

Chow Line is a service of Ohio State University Extension and the Ohio Agricultural Research and Development Center. Send questions to Chow Line, c/o Martha Filipic, 2021 Coffey Road, Columbus, OH, 43210-1044, or

Editor: This column was reviewed by Lydia Medeiros, food safety specialist with Ohio State University Extension and associate professor in the Department of Human Nutrition, College of Education and Human Ecology, at Ohio State University.

To receive a PDF file of Chow Line via e-mail, contact Martha Filipic at

Martha Filipic
Lydia Medeiros