For Catsup
For catsup, pick and wash the oysters, then run through the meat chopper or pound to a paste. To each pint, add one ounce of salt, one drachm of cayenne and one pint of white vinegar. Heat slowly, simmer for seven minutes, rub through a sieve and return to the fire. Boil for seven minutes longer and when cold add four tablespoonfuls of brandy; then bottle and seal.
This is a bottled shellfish preserve, and the reason it cannot be recommended today lies in how it is stored rather than how it is cooked. The notes below explain the measurements and the specific hazard.
- Why this one failsPureed oysters sealed cold in bottles and kept at room temperature are exactly the conditions in which Clostridium botulinum produces toxin: a low-acid, moist, protein-rich food in a sealed, oxygen-poor container. The recipe gives no acidity measurement, no processing temperature and no storage instruction, so there is no way to know whether the vinegar has brought the finished sauce below the pH 4.6 that keeps the organism in check.
- The vinegar is not a guaranteeA pint of vinegar to a pint of oyster paste sounds like heavy acidification, but oyster flesh is buffering and the strength of nineteenth-century "white vinegar" was not standardised. Sieving and boiling also drive off some acid. Without a meter reading on the finished sauce, the acid content is unknown.
- The brandy does nothing hereFour tablespoons of spirit distributed through the finished quart or so of sauce works out to somewhere around two percent alcohol by volume. That is a flavouring, not a preservative, and it is added after the boiling, when the sauce is cold and open to the air.
- "Seal" meant something differentSealing a bottle in this period generally meant a cork dipped in wax or resin. It excludes air, which is the wrong thing to do to an under-acidified seafood product; it does not sterilise the contents or the bottle.
- A drachmFor the record: the apothecaries' drachm is one-eighth of an apothecaries' ounce, about 3.9 g, so roughly two teaspoons of ground cayenne per pint of oysters. That is a fiercely hot sauce by modern seasoning habits, and heat contributes nothing to safety.
- Pick and wash"Picking" oysters means going through the shucked meats by hand for fragments of shell and bits of the frilled mantle, which are gritty. The step is still worth knowing for any oyster dish.
- If you want oyster catsupUse a current, tested recipe from a food-preservation authority, one that specifies either refrigeration with a short use-by window or a measured canning process.
Before catsup meant tomatoes it meant almost anything strained, salted and bottled to be splashed into a sauce or a stew: mushroom, walnut, cucumber, and above all fish. The word is generally traced to a Southeast Asian fermented fish brine, and the seventeenth- and eighteenth-century English versions that followed it were savoury liquid condiments in the same family as anchovy essence and the bottled sauces that became Worcestershire. Oyster catsup belongs to that older line, and it survived in American household books well into the twentieth century, plausibly because oysters were still cheap and abundant on both coasts, hawked in the street, and pressed into fritters, stews, pies and pickles. Its appearance in the Pickles chapter rather than among the sauces may well be telling: it suggests that to the compiler this was a keeping recipe, a way of getting the flavour of the oyster season into a bottle, filed alongside the vinegar preserves that shared its method if not its safety margin.