Should you wash mushrooms?

"Never wash mushrooms, they soak up water like sponges" is one of the most repeated bits of kitchen advice there is. It sounds sensible. Mushrooms look absorbent. But it turns out to be mostly wrong for the kinds most of us buy, and right only in a narrower sense.

What actually happens when you rinse them

America's Test Kitchen weighed mushrooms before and after washing, and found that mushrooms without fully exposed gills, such as button and cremini (chestnut) mushrooms, did not absorb much water. Varieties with open, exposed gills, such as portobellos, did take on a lot of water, and for those the same source suggests brushing them clean.

So: the closed, everyday mushrooms can be rinsed. The flat, open ones and the delicate wild ones are better brushed.

What matters more than washing

Soggy mushrooms almost never come from a quick rinse. They come from:

• Washing them too early. Washed mushrooms left sitting wet in the fridge go slimy and dark. Wash them just before you cook.
• Soaking them. A quick rinse is fine; a long bath is not. Mushrooms full of grit can be swished briefly in a bowl of water, then lifted out.
• Not drying them. Spread them on a clean tea towel and pat them dry. Surface water has to steam off before they can brown.
• A crowded pan. Mushrooms are mostly water anyway. Pile them in a cold, crowded pan and they release liquid and stew. Give them room and heat.

How we clean them

• Button and chestnut mushrooms: rinse quickly under cold running water just before cooking, rubbing off any dirt with your fingers, then pat dry.
• Portobellos and other open, gilled mushrooms: wipe the caps with a damp cloth or a soft brush. Rinse the tops quickly if they are dirty, keeping water away from the gills.
• Oyster, enoki and other delicate mushrooms: usually clean already. Brush or shake them, and trim the base.
• Wild mushrooms: brush them carefully, trim and use a small knife for grit. If they are very sandy, a brief swish in water and a good dry. Only ever eat wild mushrooms that have been identified by someone who knows, and follow local rules on picking.
• Dried porcini: these are a different story: they need soaking. See how to use dried porcini.

Cooking them so it does not matter

If you cook mushrooms well, a little water from washing disappears without a trace.

1. Use a wide pan and get it properly hot with a little oil.
2. Add the mushrooms in a single layer. Cook in batches if you need to.
3. Leave them alone. They will release liquid first; let it bubble away.
4. Once the pan is dry, they start to sizzle and brown. That is when the flavour arrives.
5. Then add butter, garlic, herbs and salt.

Salting at the very start draws out more liquid, so we usually salt once they have started to colour. More on that in how to make mushrooms brown.