Go Ahead And Wash Your Mushrooms
Chances are you have been told to never wash mushrooms. Here are the facts:
Mushrooms are a fungus and they are about 90% water (we know this because dried mushrooms weigh about 10% of their original weight).
Mushrooms are grown in a rich soil-like medium made from compost, usually horse manure and horse bedding made from wheat straw according to Penn State University. Synthetic compost is the term applied to compost whose main component is not manure. It is usually made from hay and crushed corncobs. It is not as common because it is more expensive. Both require the addition of nitrogen and gypsum. The compost is allowed to sit and heat up from internal microbial activity, sometimes reaching 180°F, enough to kill pathogens. But this process is not as reliable as heating it in an oven, so, although they call the results "sterile growth medium" it is more like "pasteurized growth medium". In lay terms, sterile means "nothing is left alive". Pasteurized means "we're pretty sure nothing is left alive, and if anything is, there's not enough to harm anyone."
In harvesting, sorting, packing, shipping, and retailing, mushrooms are exposed to air and pathogens.
Some chefs say you only need to wipe mushrooms with a bristle brush or a damp paper towel to get any growth medium off the surface. This does not remove all microbes.
Some say to rinse them. Rinsing removes more microbes but does not remove them all. Washing them vigorously removes more microbes but not all of them.
The only way to make sure mushrooms are absolutely safe, or any other food for that matter, is to heat them until the microbes die. In other words, cooking them makes mushrooms safe whether you wash them or not.
Mushrooms may look like a sponge, but they are not. Above are three button mushrooms that had been in my fridge for a week, so I'm sure they had dehydrated a bit. I weighed them on a good OXO digital scale. It is not lab quality, but pretty accurate. On the left, they are right out of the box, 2 3/8 ounces. In the center they have been rinsed and I scrubbed off dark flecks. I then patted them dry with a paper towel. At 2 5/8 ounces, the water gain is 11%. The mushrooms at right have been soaked in water for 45 minutes. They have gained about 25% and now weigh 3 ounces.
Finally, I have tasted washed and brushed mushrooms side by side. I can't tell the difference.
My advice for handling
Buy mushrooms that are as fresh as possible. The umbrella head of common button mushrooms opens as they age exposing the gills. Try to select for those that are close to closed. They also get brown as they age, try to pick unblemished mushrooms. But older mushrooms are really fine when cooked and mushrooms should be cooked.
Just before using them, rinse whole mushrooms vigorously in cold water and try to remove dirt on the surface. Pat dry. Don't soak or peel mushrooms.
Don't rinse sliced mushrooms. Sliced mushrooms have a lot more surface area so washing them will add a lot more water. In fact, don't buy sliced mushrooms. They oxidize rapidly.
If the stems are woody, remove them, freeze them, and use them in soups and stocks. Otherwise just slice off the fibrous bottom of the stem and discard it.
This page was revised 2/19/2014
About this website
AmazingRibs.com is all about the science of barbecue, grilling, and outdoor cooking, with great BBQ recipes, tips on technique, and unbiased equipment reviews. Learn how to set up your grills and smokers properly, the thermodynamics of what happens when heat hits meat, as well as hundreds of excellent tested recipes including all the classics: Baby back ribs, spareribs, pulled pork, beef brisket, burgers, chicken, smoked turkey, lamb, steaks, barbecue sauces, rubs, and side dishes, with the world's best buying guide to barbecue smokers, grills, and accessories, edited by Meathead.
Advertising on this site
AmazingRibs.com is far the most popular barbecue website in the world and one of the 50 most popular food websites in the US according to comScore and Quantcast. Visitors and pageviews increase rapidly every year. Click here for analytics and advertising info.
| Weights, Measures, Conversions | Tips & Techniques | Recipes | Equipment Reviews | BBQ Culture & History |
| My Ingredients | BBQ Joints | About Us | Blog | Links | Newsletter | BBQ Tunes |
| Privacy Promise, Code of Ethics, Other Legal Terms | Advertising & Sponsorship Opportunities |