Important: Safety Warning
This page gives advice for salvaging or disguising food that has begun to spoil. Spoiled food can carry dangerous bacteria and toxins that no washing, soaking, or seasoning removes; it should be discarded.
This information has been left in for historical purposes but should not be acted upon.
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Pickled Onions
Peel the small white button onions, and pour over them boiling brine that is sufficiently strong to bear an egg. Let it stand twenty-four hours, drain and put in bottles. Take sufficient vinegar to cover the onions, add spices to taste, and pour over the onions boiling hot. When cool fasten, and they will be ready to use in four or five days and will keep all winter. If the slightest mould appears on the surface, drain off the vinegar and cover with fresh, hot vinegar.
This is a genuine recipe, but it belongs to an era before anyone measured the acidity of vinegar or the pH of a finished pickle. The points below explain where it fails rather than how to fix it; for pickled onions today, follow a tested current recipe with stated vinegar strength and processing times.
- The mould instruction is the fatal lineDraining off vinegar and topping up with fresh hot vinegar treats visible mould as a cosmetic problem. Surface moulds and film yeasts consume the acid in the brine, raising the pH of the whole jar, and mould growth extends well below what is visible. A jar that has grown mould should be discarded, not refilled.
- Unspecified vinegar strengthNineteenth-century household vinegar ranged widely in acidity, some of it home-made from cider and considerably weaker than the 5 percent standard. "Sufficient vinegar to cover" with "spices to taste" gives no way to know whether the finished pickle sits below pH 4.6, which is the line that matters for onions.
- Onions are a low-acid vegetableAlliums have no useful acidity of their own and are dense enough that acid penetrates the layers slowly. Pickles of this kind rely entirely on the vinegar to acidify the interior of each onion, and a twenty-four-hour salt soak followed by a single hot pour does not guarantee it.
- Sealing without processing"When cool fasten" means capping jars of cooled liquid and setting them aside. There is no boiling-water process, no headspace given, no seal check. Bottles filled and closed this way are not shelf-stable, whatever the recipe promises about keeping all winter.
- Ambient storage for monthsThe keeping claim assumes a cold larder or cellar in an unheated house, far cooler than a centrally heated modern kitchen. The same jars in a warm cupboard are a different proposition entirely.
- What the brine test meantBrine "strong enough to bear an egg" is old shorthand for a heavily salted solution, judged by whether a fresh egg floats rather than sinks. It is a rough indicator of salt concentration and nothing else; it says nothing about the safety of the finished pickle.
Pickled onions were one of the workhorses of the English and American store cupboard, made in autumn when the small white "button" or silverskin onions came in and eaten through the winter alongside cold meat, bread and cheese. The two-stage method here, a strong salt soak followed by spiced vinegar, is a standard household technique of the eighteenth and nineteenth centuries: the salt draws out water so the onions stay firm and the vinegar is not diluted into weakness. Household cookbooks of this period commonly assumed a cook who judged brine by floating an egg and vinegar by taste; a domestic kitchen had no practical means of measuring acidity, and the understanding that pH, not sourness, determines whether a pickle is safe belongs to the twentieth century. The cheerful advice about mould is also of its time, when a skin of growth on the surface of a crock could be treated as an ordinary nuisance to be skimmed off rather than a sign that the preserve had failed.