Mushrooms, Dried
Wipe them clean and take away the brown part and peel off the skin; lay them on sheets of paper to dry, in a cool oven, when they will shrivel considerably. Keep them in paper bags, which hang in a dry place.
When wanted for use, put them into cold gravy, bring them gradually to simmer and it will be found that they will regain nearly their usual size.
A drying and storage method rather than a dish. The instruction that matters is the drying itself: mushrooms are about 90 per cent water, and anything less than brittle-dry will mould in a paper bag within a fortnight.
- "A cool oven"Around 200-225F, with the door propped slightly ajar so moisture escapes. A modern oven's lowest setting, or a dehydrator at 130-140F, does the same job; expect 4-8 hours depending on thickness.
- "The brown part"Most likely the gills, which in the large open field mushrooms of the period would be dark and would bleed inky juice into a dish. Tight-capped white buttons have pale gills and need no such trimming; creminis darken as they open.
- Skip the peelingPeeling was standard for field-gathered mushrooms with tough, gritty cuticles. Cultivated mushrooms are grown in pasteurised compost; wipe them and leave the skin on.
- Slice, don't dry wholeWhole caps dry unevenly and can stay damp at the centre. Cut 1/4-inch slices and lay them so they do not touch; parchment or a wire rack beats sheets of paper.
- Test for drynessA properly dried slice snaps rather than bends. If it is leathery it still holds water and will spoil.
- StoragePaper bags in a dry place work only in a genuinely dry room. An airtight jar kept dark is safer, and any sign of condensation on the glass means the mushrooms go back in the oven.
- RehydratingThe cold-gravy start is sound practice: a slow warming is generally held to rehydrate dried mushrooms more evenly than dropping them into hot liquid. Twenty to thirty minutes brought slowly to a simmer suits them, and the soaking liquid should be used, not discarded.
- YieldRoughly 1 lb of fresh mushrooms gives 1 1/2 to 2 oz dried. An ounce of dried, rehydrated, is enough to flavour a stew for four.
- IdentificationIf gathering wild, only mushrooms identified with certainty should be dried. Drying concentrates whatever is in the mushroom and does not neutralise the toxins of look-alike species.
Drying was the oldest way of keeping the short mushroom season, which in Britain ran through late summer and autumn when field mushrooms and horse mushrooms appeared in pasture after rain. Beeton's household books give a good deal of space to mushrooms as a flavouring agent, in ketchups, powders and pickles, alongside dishes in which they stand alone; commercial cultivation was still small-scale in the mid-nineteenth century, and a cook who wanted mushroom flavour in February relied on what had been put by, at home or by a supplier. The gradual warming in cold gravy reflects a kitchen habit that ran through all of Victorian reconstituting, whether of dried peas, isinglass or salt fish, and the claim that the caps "regain nearly their usual size" is optimistic: they recover volume but never the firm texture of a fresh mushroom, which is part of why dried ones ended up in gravies and ragouts rather than on toast.