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Oyster Catsup
Pound two dozen oysters with three anchovies in a mortar and season with one-fourth ounce each of ground cloves, cayenne pepper and ground mace. Mix their liquor with them, turn them into a lined saucepan, pour in a pint of white wine and two wineglassfuls of brandy. Place the catsup over a slow fire until boiling, then strain it through a fine silk-sieve. When cold, pour the catsup into bottles and keep them tightly corked for use.
This is a nineteenth-century bottled sauce, and the preserving method is the problem rather than the flavour. The notes below explain the units and the specific reasons this one should not be reproduced.
- Why it fails: low-acid shellfish, bottled and storedPounded raw oysters and their liquor are a low-acid, high-protein food. The recipe brings the mixture just to boiling, then bottles it cold and corked with no acidification, no measured salt, no heat process and no refrigeration. That is the classic set of conditions for Clostridium botulinum to grow in an oxygen-free bottle, and the toxin it produces is not detectable by smell or taste.
- The alcohol is not a preservative hereA pint of white wine and two wineglassfuls of brandy sound protective, but diluted through two dozen oysters and their liquor the finished sauce is somewhere around 10 percent alcohol by volume, and less after boiling — far below the level that would inhibit spore-forming bacteria. Many bottled catsups of the period relied on heavy salting; this version specifies no salt at all beyond what the oyster liquor and anchovies bring.
- "Until boiling" is not a processReaching a boil once kills vegetative bacteria but not botulinum spores, which survive well above 212F. Commercial and home preserving of low-acid foods requires pressure processing at measured temperatures and times. If you want an oyster sauce, use a current recipe intended for refrigerated short-term use.
- WineglassfulIn American cookbooks of this period a wineglass is reckoned at about 2 fluid ounces, so two wineglassfuls is roughly half a cup. A pint is 16 fluid ounces.
- A quarter ounce each of cloves, cayenne and maceA quarter ounce of ground cayenne is roughly a tablespoon or so by volume — the seasoning here is aggressive, and sauces of this kind were generally used a spoonful at a time in stews and fish sauces rather than eaten on their own.
- Lined saucepan and silk sieve"Lined" means tinned copper, specified so the acid and the spices would not react with bare copper; an enamelled or stainless pan is the modern equivalent. A fine silk sieve gave the closest straining available in this period.
Before catsup meant tomatoes, it meant a whole family of dark, salty, keeping sauces — mushroom, walnut, oyster, anchovy — kept bottled in the larder and used a spoonful at a time to deepen gravies, fish sauces and made dishes. The word itself is generally traced to a Southeast Asian fermented fish brine, kê-tsiap or similar, and appears in English cookery from the late seventeenth century onward; oyster catsup sits close to that origin, being essentially a fortified, spiced fish sauce. Recipes of this kind assumed a larder stocked with such bottled seasonings at a time when oysters were cheap and abundant. The confidence about corking and keeping reflects a period before the food safety understanding that would later make such a method unacceptable.