Should Mushrooms Be Washed, or Wiped Clean with a Damp Cloth?

A brief rinse doesn't seriously damage a cultivated mushroom; the surface may look porous, but the flesh underneath is largely water-resistant, so a few seconds under running water followed by a quick pat-dry doesn't ruin the texture. Soaking is a different matter — left in water for a while, mushrooms genuinely start to absorb it, and instead of releasing that water cleanly when cooked, they turn rubbery. Wiping with a damp cloth or a soft brush is enough for cultivated mushrooms grown in clean conditions, and it keeps contact with water to a minimum. Wild mushrooms, or ones grown closer to the soil, generally clean up better with a wash than with wiping. Do mushrooms really soak up water? A mushroom's cell structure is spongy, but the amount of water it actually absorbs during brief contact is measurably small; the real issue isn't the water itself but how long the mushroom stays in it. The difference between a few seconds of rinsing and a 5–10 minute soak is clearly noticeable in the texture once cooked. Sliced mushrooms absorb more water than whole ones, because the cut surfaces have lost their natural protection. For this reason mushrooms should be cleaned before slicing, and contact with water kept as brief as possible once they are sliced. This difference shows up in the pan too: a mushroom that has soaked up too much water releases it first when it hits the pan, and browning doesn't start until that water evaporates, which makes cooking take far longer than expected. When is wiping with a damp cloth enough? Cultivated mushrooms grown in a controlled, sterile peat-based growing medium generally carry no visible dirt; the thin layer of dust on the surface wipes off easily with a damp paper towel or a soft brush. This method keeps the mushroom from touching water at all, and it browns better when cooked as a result, since there's no extra moisture sitting on the surface. The thin membrane under the cap is especially delicate; wiping it without pressing too hard keeps the mushroom's shape intact. How should mushrooms grown closer to the soil be cleaned? Chestnut mushrooms, portobellos and wild-picked mushrooms usually carry visible soil at the base of the stem and in their folds; a brief rinse works better than wiping for these. After washing, the mushrooms need to be dried thoroughly with a paper towel, not left wet. Trimming off the tough, sand-holding base of the stem with a knife before washing makes it easier to remove the remaining soil as well. How should cleaned mushrooms be stored? Washed mushrooms need to be dried thoroughly before going into the fridge; leftover moisture leaves a mushroom with a slimy surface within a few days in a sealed container. Mushrooms stored in a paper bag balance moisture better than ones in a plastic bag and stay fresh longer. If cleaned mushrooms won't be used and need freezing, sautéing them lightly first to release their moisture before freezing keeps them from turning rubbery once thawed. Leaving mushrooms in their original plastic packaging is one of the habits that can make them spoil quickly; the packaging traps moisture inside, and within a few days the mushrooms soften and start to darken in their own condensation.