Important: Safety Warning
This page offers rules for telling edible mushrooms from poisonous ones. No such rules are reliable, and these identifications predate modern mycology. Deadly species closely resemble edible ones, and mistakes are regularly fatal. Never eat a wild mushroom on the strength of this text.
In addition, this page describes home-canning methods from before the causes of botulism were understood. Canning low-acid foods without a pressure canner, as described here, can allow the growth of Clostridium botulinum, whose toxin is among the deadliest known. Follow current USDA home-canning guidelines instead.
This information has been left in for historical purposes but should not be acted upon.
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Pickled Mushrooms
Wash thoroughly, and, if of convenient size, put whole into glass jars. Set these on the rack of a steam kettle (with a cloth on the rack beneath the cans). Put in warm water to cover the rack and let steam fifteen minutes. Have ready enough vinegar scalded, with peppercorns, cloves, mustard seed, celery seed, bay leaves, and chili peppers, to fill the jars. Pour this into the jars. Adjust the rubbers and covers, and let cook five or six minutes, then screw down the covers, and set aside. A tablespoonful of mixed spices will be enough for a quart jar.
Pickled Mushrooms No. 2 If the Agaricus campestris be the variety to be pickled, remove the caps from the stems or leave them in place as desired. Peel the caps and put them into fruit jars; for each two jars desired, take a third jar and partially fill it with the mushrooms. Set the jars on a folded towel, laid on the rack of a steam kettle, and pour in cold water to come half way to the top of the jars; put the lids over the jars and cover the kettle. Let cook three fourths an hour after boiling begins, then fill the two jars from the third. Have ready a quart or more of vinegar, scalded, with two tablespoonfuls of assorted spices, cloves, mace, celery seed, mustard seed, tiny, red-pepper pods, black pepper-corns and the like. Pour the vinegar into the jars to fill them to overflow; adjust the rubbers and covers and let cool in the kettle.
This is a home-canning procedure for a low-acid vegetable, and it falls outside every current safety guideline. The notes below explain the specific failures rather than offering a corrected method.
- Mushrooms are the classic botulism vehicleClostridium botulinum spores live in soil and travel into the jar on the mushrooms. Nothing in either method reaches the temperature needed to destroy them, and a sealed jar of moist, low-acid fungus is close to an ideal incubator. Canned mushrooms have a long documented association with botulism outbreaks.
- The acidity is never measuredSafety in a pickle depends on the finished acidity of the whole jar contents, not on the fact that vinegar was used. The recipe specifies neither vinegar strength nor a mushroom-to-vinegar ratio, and mushrooms are watery enough to dilute the brine substantially once packed. Period vinegar also varied widely in acetic acid content.
- Open-kettle sealingBoth versions heat the jars in a partly filled kettle and pour in scalded vinegar; the first then screws down the covers and sets the jars aside, the second lets them cool in the kettle. The seal here is formed by cooling, not by a measured process at a known temperature, and nothing in either method tells you what temperature the centre of a packed quart of mushrooms actually reached.
- "Steam fifteen minutes" is not a process timeFifteen minutes in warm-water steam, or three-quarters of an hour with water halfway up the jars, tells you nothing about the temperature reached at the cold spot in the centre of the pack. Modern process times are tied to a specific jar size, a specific fill, and a verified temperature.
- Wild-gathered Agaricus campestrisThe second method assumes the cook has correctly identified the field mushroom. Young Agaricus buttons are confusable with lethal white Amanita species, and the yellow-staining Agaricus xanthodermus also grows in the same grass. Preserving a large batch multiplies any single identification error across many jars.
- Rubbers and screw coversThe jars in question sealed with a separate rubber ring under a glass or zinc lid. That closure system is no longer manufactured to any current standard, and the two-piece lids sold today behave differently under heat.
- What to do insteadIf you want pickled mushrooms on a shelf, follow a current tested recipe from a food-preservation authority, which will specify vinegar strength, acid ratio and a measured boiling-water process. Refrigerator pickles, eaten within a few weeks, avoid the question entirely.
Pickled mushrooms belong to a long English and American tradition of preserving fungi in vinegar and spice, alongside mushroom ketchup and mushroom powder, all of them ways of keeping a crop that appears suddenly in pastures after rain and rots within days. The naming of Agaricus campestris in the second method reads as a period marker: household books of what appears on stylistic grounds to be the turn of the century were often written for readers who might gather the common field mushroom themselves, though the name covered cultivated mushrooms too, and popular mycology guides for the amateur collector were being published in the same decades. The spice mixture here — cloves, mace, celery seed, mustard seed, peppercorns and small red pods — is the standard "mixed pickling spice" of the era, measured by the tablespoon per quart. What the recipe also records is the state of home canning before the science caught up: heating jars on a rack over water, pouring in scalded vinegar, and trusting the vinegar to do the rest, and the hazards of low-acid canning were not widely understood by domestic cooks until well into the twentieth century.