How to Store Mushrooms: Fridge, Drying and Freezing Guide

Fresh mushrooms are mostly water, and they keep breathing after they are picked. Store them sealed and they sweat and turn slimy; leave them open and they shrivel. Get the balance right and most will keep a week, some much longer. Here is how we store the mushrooms that come off the MushRealm bench, with shelf lives by species and the best ways to dry and freeze a big harvest.

Why mushrooms spoil

Two things go wrong:

• Too much moisture. Mushrooms release water vapour as they respire. Trapped in a sealed container, it condenses on their surface, and wet mushrooms go slimy and start to break down fast.
• Too little moisture. Left uncovered in a dry fridge, they lose water, wrinkle and turn leathery.

The goal is a container that lets moisture out slowly. A paper bag does exactly that.

The paper bag method

1. Do not wash them. Water on the surface is the fastest route to slime. Brush off dirt or substrate and wash just before cooking, if at all.
2. Keep clusters whole. Oyster clusters keep better attached to their base than torn into pieces. Remove only damaged bits.
3. Bag them loosely. Put them in a paper bag, fold the top over once and leave some air inside. No paper bag? Line a container with kitchen paper, add the mushrooms in a single layer and cover loosely with another sheet.
4. Use a main shelf. A fridge running at 1 to 4°C (34 to 40°F) is ideal. The crisper drawer tends to be humid, which is why mushrooms often go slimy there.
5. Keep them away from strong smells. Mushrooms pick up odours from things like onions, garlic and fish.
6. Packaged mushrooms: the perforated film on shop-bought packs is fine until opened. After that, move them into paper.

How long fresh mushrooms last

These are typical fridge lives for whole, unwashed mushrooms in a paper bag. Home-grown mushrooms picked at the right moment sit at the top of each range; shop-bought ones may already be a few days old.

For more on how the oyster types differ, see our guide to oyster mushroom varieties.

Tips for home growers: store better by harvesting better

Shelf life starts on the bench, not in the fridge.

• Harvest at the right moment. Pick oysters while the cap edges still curl downward. Once caps flatten and the edges turn up, they are older and will not keep as long.
• Do not mist right before harvest. Wet caps go into the bag wet. Mist after you pick, not before.
• Chill quickly. Get them into the fridge within an hour or two of harvest.
• Twist off the whole cluster, then trim off any substrate stuck to the base before bagging.

Our guide to getting a second flush covers what to do with the block once you have harvested.

How to dry mushrooms

Drying concentrates flavour and lets you keep mushrooms for months. Shiitake dries exceptionally well, oysters and king oysters dry well for soups and broths, and dried mushrooms can be ground into a savoury seasoning powder. Lion's mane is better cooked and frozen, as its texture suffers when dried and rehydrated.

In a dehydrator

1. Slice mushrooms about 5 mm (1/4 in) thick, or tear oysters into thin strips.
2. Spread in a single layer on the trays without overlapping.
3. Dry at 50 to 55°C (125 to 135°F) for 4 to 8 hours, depending on thickness.
4. They are done when they are cracker-dry and snap rather than bend.

In the oven

1. Lay slices on a wire rack set over a baking tray.
2. Set the oven to its lowest setting, ideally 60 to 75°C (140 to 170°F).
3. Prop the door open slightly with a wooden spoon to let moisture escape.
4. Dry for 2 to 4 hours, turning the slices halfway, until they snap.

Storing and using dried mushrooms

Cool completely, then pack into airtight jars and keep somewhere cool and dark. Check the jar after a day: any condensation means they need more drying. For the best flavour, use them within 6 to 12 months.

To rehydrate, soak in hot (not boiling) water for 20 to 30 minutes. Strain the soaking liquid through a fine sieve or coffee filter and use it as stock.

How to freeze mushrooms

Raw mushrooms freeze poorly: ice crystals break their cells and they thaw limp and watery. Cooking them first gives a much better result.

1. Cook the mushrooms using the dry sauté method with a little butter or oil, or steam them for 3 to 5 minutes.
2. Cool them completely.
3. Pack flat in freezer bags, press out the air and label with the date.
4. Use within about 3 to 6 months for the best flavour and texture.
5. Cook straight from frozen in soups, sauces, risotto, pasta and stir-fries.

For a big harvest, chop mushrooms finely and cook them down slowly with shallot and butter until dry and jammy, then freeze in ice cube trays. Each cube adds a hit of mushroom flavour to a sauce.

Signs mushrooms have gone off

Throw mushrooms out if you notice any of these:

• A slimy or sticky surface
• Dark, wet or mushy patches
• A sour, fishy or ammonia-like smell
• Fuzzy mould of any colour
• Soft, collapsing flesh

Some changes are just aging and fine to cook: slight wrinkling, a few dry edges, or darkening gills on button mushrooms, as long as they smell clean. When in doubt, throw them out.

Storage does not make any mushroom safe if you do not know what it is. If you forage, never eat a wild mushroom unless its identity has been confirmed by an experienced local expert, and remember that some deadly species look like edible ones.

Quick checklist

• Do not wash before storing.
• Paper bag, folded loosely, on a main fridge shelf.
• Keep oyster clusters whole.
• Pink and golden oysters: cook within 2 to 3 days.
• King oyster and shiitake: a week or more.
• Dry at 50 to 55°C (125 to 135°F) until they snap.
• Freeze cooked, not raw.
• Slime, sour smell or mould means it goes in the bin.

If you want the freshest oysters possible, grow them yourself. Our grow kit is a simple place to start, and lion's mane and shiitake are rewarding next steps.

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