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Mushroom Catsup
Gather large flap mushrooms for this purpose in the month of September. If the weather be showery, wait until the mushrooms have had a few hours of sunshine, for no water should enter into the composition of catsup. Break into an earthenware pan as many mushrooms as it will hold. Let them be clean, and quite free from grit or dirt, and that portion of the stem should be removed to which the soil adheres. Sprinkle salt among them, and put a layer over the top (from 6 to 8 ounces will be enough for a peck of mushrooms). Cover them for two days, occasionally stirring them during the time, then strain through a sieve without giving the mushrooms any pressure. To each quart of the juice so gained allow three blades of mace, 1/2 an ounce of black peppercorns, the same of sliced ginger, with half the quantity of allspice, a few cloves, and more salt if required. Boil the juice for fifteen minutes, uncovered, and before putting in the spice; add the spice, and boil twenty minutes more. Fill bottles when quite cold. Wax the corks to exclude the air.
This is the classic English mushroom ketchup, and it is worth reading as a document rather than a project. As written it produces an uncooked-strength, low-acid liquid sealed cold under wax and kept at room temperature, which is exactly the condition modern preserving guidance rules out.
- Why it fails: no acid, sealed anaerobicallyThere is no vinegar anywhere in this formula. Strained mushroom juice is a low-acid liquid, and corking it cold and sealing the cork with wax creates the oxygen-free environment in which Clostridium botulinum spores can germinate and produce toxin. Boiling — fifteen minutes before the spice and twenty minutes after — kills cells but does not destroy spores, and the bottles are never processed after filling.
- Why it fails: the salt is unmeasurable in the finished liquidSix to eight ounces of salt is spread over a whole pan of mushrooms, but only the drained juice is kept. How much of that salt ends up in the quart of liquid depends entirely on how wet the mushrooms were, so there is no way to know whether the finished ketchup is preserved by salt or merely seasoned by it. Safe salt-preservation needs a measured brine concentration.
- Why it fails: two days at room temperature before any heatThe mushrooms are left covered and stirred for two days at ambient September temperature. That standing period is a deliberate part of the extraction, but it is also two days of uncontrolled microbial activity in a low-acid food before the first application of heat.
- Wild gathering"Large flap mushrooms" is most likely mature open-capped field mushrooms of the Agaricus sort, gathered from pasture, though the term is vernacular and imprecise. Dangerous species can resemble Agaricus closely enough — particularly at the button stage — that field collection is not a beginner's undertaking, and the recipe assumes a familiarity with local ground that most readers no longer have.
- The units, for referenceA peck is eight dry quarts, roughly two gallons of loose mushroom caps and a large quantity by any modern standard. A blade of mace is one lacy segment of the aril from a single nutmeg; three blades per quart is a light hand.
- If you want mushroom ketchupUse a current, tested recipe with a measured proportion of vinegar and a specified processing or refrigerated storage instruction. The spicing here — mace, black peppercorns, ginger, allspice, a few cloves — is sound and can be read as a guide to flavour, nothing more.