Home › The Principles of Cookery › Oysters, to Keep
Oysters, to Keep
Cover the oysters with cold salt and water, allowing six ounces of salt to each gallon of water. When they have lain for twelve hours, drain them, and leave them bare for the same length of time, then put fresh salt and water over them again, and repeat this change every twelve hours until the oysters are wanted for the table. They may be kept alive thus for a week or ten days in moderate weather. When oysters are carefully and tightly packed in barrels directly they are taken from the beds, they will keep good for some days without water. A handful of oatmeal is occasionally put into the water which covers them, with the idea of feeding the oysters, but though this improves their appearance, it quite spoils their flavour.
This is a holding method from an era without refrigeration, and it is the one part of oyster cookery that has not survived. The instructions below explain the terms and then why the procedure itself is no longer defensible.
- Why this fails nowThe method keeps live oysters at ambient temperature for up to ten days, in water changed only twice a day. Vibrio parahaemolyticus and V. vulnificus multiply rapidly in shellfish held above about 50F, and oysters intended for raw or lightly cooked service must be kept continuously chilled at roughly 34-45F from harvest onward. The recipe's only concession to temperature is the phrase 'in moderate weather', which is no control at all.
- The water is the second problemOysters held in a closed volume of untreated water re-filter their own waste and any bacteria in it. Modern commercial purification uses flowing, UV-treated or otherwise sanitised seawater with monitored salinity and temperature, and is a regulated process rather than a kitchen one.
- Dead oysters cannot be sorted out by eyeDead oysters are hard to sort out by eye -- After several days of this treatment an unknown proportion of the batch will be dead, and a shell that gapes or feels slack is a poor guide once the animal has been sitting in brine. Buy oysters from a supplier who can give you a harvest date and keep them cold, cupped side down, under a damp cloth, for the short window the supplier states.
- "Six ounces of salt to each gallon"An imperial gallon is 160 fl oz, so this is roughly a 3.75 per cent brine by weight of water -- deliberately close to the salinity of seawater, which is about 3.5 per cent. The intention was to imitate the bed, not to cure anything.
- "Leave them bare"Bare means out of the water entirely, lying in the shell. Oysters do survive periods of exposure at low tide; it is not a draining step before cooking.
- The oatmealFeeding oysters oatmeal to plump them is mentioned in period cookery writing, and Cassell's is blunt about the result: it improves their appearance but spoils their flavour.
- The barrelsTight packing without water works because it holds the shells closed so the oyster retains its own liquor. Commercial oysters still travel this way, in mesh or crates, but under refrigeration throughout.
- If you want oystersFollow current handling guidance from your fishmonger or national food safety agency rather than any nineteenth-century holding method.
Cassell's was written for households buying oysters by the barrel, and a cook might reasonably take delivery of far more than could be eaten in a day. With no mechanical refrigeration in the domestic kitchen, keeping shellfish meant keeping it alive, and instructions like these appear in general cookery dictionaries of the period alongside advice on ice chests and cool larders. The remark about oatmeal is a small piece of trade lore: plumping oysters in fresh or oatmeal-laced water was practised, and condemned by writers who cared about flavour. Within a generation or two the whole problem dissolved, as rail transport, ice and then refrigeration made it possible to sell oysters quickly instead of storing them, while the collapse of the great English oyster beds turned the barrel-load into a delicacy bought a dozen at a time.