Potted Fish
Pick the cold fish to pieces, season with salt, pepper and a very little mace, then put into a jar, tie tightly with a piece of muslin, then cover this with a paste made from flour and water, stand the jar in a pan of water and bake in a moderate oven one hour. When done and cold, pound the fish to a paste, pack it back into the jar and cover with melted butter.
This is a preserving method, not a supper dish: the fish is sealed in a jar, baked in a water bath, pounded, and then shut away under a butter seal for keeping. That last step is what puts it beyond modern practice.
- Why the butter seal is the problemA layer of melted butter over pounded fish excludes air, and cooked fish held without oxygen at room or cellar temperature is the textbook setting for Clostridium botulinum to produce toxin. The toxin has no smell or taste, and nothing in the recipe brings the sealed pot back to a temperature that would destroy it.
- No measured cure, no measured heatThe seasoning is "salt, pepper and a very little mace" — quantities that season but do not preserve. There is no weighed salt ratio, no acidification, no stated internal temperature and no storage instruction, so there is no way to judge whether a batch is safe.
- The second handling stageAfter baking, the fish is uncovered, pounded to a paste by hand, and repacked. Every bit of that reintroduces bacteria into a product that will then be sealed and kept, and the pounding is done when the fish is cold rather than hot.
- It begins with leftovers"Cold fish" means fish already cooked and cooled, with no indication of how long it has been standing or at what temperature. Starting a keeping preparation from already-cooked, already-handled fish is what modern food safety rules out.
- Hot weather makes it worseWarmth makes it worse -- Warmth is exactly what accelerates growth in a sealed, low-acid, moist protein. If you want a fish paste, use a current recipe that is refrigerated and eaten within a few days.
- What the odd steps were forThe muslin and the flour-and-water paste are a disposable lid: the paste sets hard in the oven and keeps steam out of the jar during the water bath. It is a sealing device, not an ingredient, and it was chipped off and thrown away.
- MaceMace is the lacy outer covering of the nutmeg seed, warmer and less sweet than the nutmeg itself. It was a standard aromatic in English potted meats and fish.
Potting was one of England's main methods of keeping cooked meat and fish before canning, and it runs through household books from the seventeenth century to the early twentieth: the flesh was seasoned, cooked in a covered pot, pounded to a paste with butter, packed down and sealed under a layer of clarified butter that hardened into an airtight cap. Potted salmon, potted char from the Lake District and potted shrimps were sold commercially and sent considerable distances, and the technique is a forerunner of the tinned fish pastes that later replaced it. A potted jar needed no cooking at serving time and could be sliced or spread for a cold luncheon.