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Acid Liquors
Vinegar. (Impure Dilute Acetic Acid.) Vinegar is made by the oxidation of alcohol, either directly or through the medium of a ferment, or by the distillation of wood; the latter is known as pyroligneous acid. Any substance capable of fermentation or any containing alcohol is suitable for making vinegar. It is made in the slow way from wine, cider, beer, sugar, or honey vegetables; in the quick way from a spirit preand water, whiskey and water, juice of plants and pared for the purpose.
Slow Method of Making Vinegar.
This is the process usually adopted in the small scale. The "wash," as any weak alcoholic liquor is called, should be weak, from 5 to 10 per cent. of alcohol is best, too strong a liquor will ferment very slowly; the strength is best judged by the taste. The temperature should be from 74° to 86° Fahr. Sour beer, wine, or cider are better than good liquors. The addition of sugar, honey, or other sweet matter with a view of strengthening the vinegar is not to be recommended, as it renders the vinegar liable to spoil. Ordinary fermented liquors are quite alcoholic enough. The best ferment is vinegar; an old cask in which good vinegar has been kept is the best to ferment in. Other ferments are used, as bread soaked in brewer's yeast, sour dough, dough of wheat and rye flour soaked in cream of tartar and vinegar; all these are used in small quantity, a few ounces to a barrel of wash. Vinegar made with them is more apt to spoil. The more ferment present the quicker the process.
The wash is put into the cask, which is best painted black in order to absorb the sun's rays when the weather is cool; the bung is left out, the bung-hole covered with a piece of slate, and in about 4 weeks the acetification is complete. The lower the temperature the slower the change.
To Purify Vinegar.
After all the mothers are deposited, draw it off into a vessel filled with beech-shavings, and let it stand in a cool place until clear. Vinegar is apt to be infested with flies (Musca cellaris), and eels (Vibrio aceti). These may be killed by passing it through a coiled tube dipped in boiling water.
Vinegar (especially when weak) if exposed to the air becomes thick or mothery, and deposits a mucilaginous substance; the vinegar becomes weak and mouldy as this change goes on.
When vinegar is barrelled, a pint of spirits should be added to each barrel to secure its keeping. It should be kept in a cool place. Varieties of Vinegar.
Wine Vinegar, made from wine, contains citric and tartaric acid, and a small portion of acetic ether, which communicates an agreeable flavor.
This is a working description of acetic fermentation rather than a measured recipe, and most of it still holds. A few of its assumptions and hazards need translating.
- The hinge: air, not heatAcetification is an aerobic process — the bacteria need continuous contact with oxygen at the surface, which is why the bung is left out and only loosely covered. Seal the vessel and you get no vinegar; agitate the surface mat repeatedly and you slow it down. Cover the opening with a cloth secured by a band, which does the same job as the slate while keeping fruit flies out.
- The wash strengthThe 5 to 10 per cent figure is still the working range. Above roughly 12 per cent the alcohol inhibits the bacteria and the process stalls; below about 4 per cent the finished vinegar will be too weak to keep and will spoil. Ordinary cider, table wine cut with water, or flat beer all sit in the right band.
- Temperature74 to 86 Fahrenheit is 23 to 30 Celsius, and that remains the accepted range. A warm cupboard or the top of a fridge will do it; below about 60F the culture goes dormant. The black-painted cask set in the sun is a nineteenth-century answer to a problem now solved by indoor heating.
- The right starterIgnore the bread, brewer's yeast and sour dough. Those are alcoholic ferments and, as the text half-admits, vinegar made with them is apt to spoil. Use a live unpasteurised vinegar or a mother of vinegar as the seed — the author's own first recommendation, and the only one that introduces the correct bacteria.
- "Mothers" and "eels"The mother is the cellulose mat produced by the acetic bacteria — harmless, and worth keeping for the next batch. The eels are Turbatrix aceti, a tiny nematode that is unappetising but not a pathogen. Heating the finished vinegar to about 140-150F for a few minutes kills both them and the active culture; the coiled tube in boiling water is a crude heat exchanger doing exactly that.
- Beech shavingsUntreated beech shavings were the standard packing material for vinegar generators — they give the bacteria enormous surface area and act as a clarifying filter. A modern equivalent is simply to rack the vinegar off the sediment and let it settle, or pass it through a coffee filter.
- Four weeks is optimisticWith a vigorous mother and a warm room, three to four weeks is achievable. A cool room or a sluggish culture can stretch it to two or three months. Judge by taste and smell rather than the calendar; the sharp alcoholic edge should be entirely gone.
- Unknown acidity means no picklingCommercial vinegar is standardised at 5 per cent acetic acid, and preserving recipes assume that number. Home vinegar can land anywhere from 2 to 7 per cent. Use it for dressing and cooking, but do not use it for pickles or any shelf-stable preserve unless you have titrated it or bought a test kit.
- Pyroligneous acidThe wood-distillate vinegar mentioned in the first line was a real industrial product but is not a food ingredient by current standards; crude wood distillates carry methanol and polycyclic aromatic compounds. The passage is describing it, not instructing you to make it.
The word is simply French vin aigre, sour wine, and the process was for most of history an accident that people learned to manage rather than an invention. What separates this entry from a medieval one is the vocabulary: the compilers name the organisms — Musca cellaris for the vinegar fly, Vibrio aceti for the eel — and speak of oxidation of alcohol, language that belongs to the chemistry of the early nineteenth century rather than to folk brewing. The "quick way" glanced at here is the generator method, generally traced to Schützenbach in Germany in the 1820s, in which the wash trickles over a tower packed with beech shavings and meets a rising draught of air, cutting weeks to days. That the book still recommends the slow cask for small-scale work is honest: it needed no equipment beyond a barrel that had held vinegar before, and the household that made its own cider made its own vinegar from whatever cider had turned. Pasteur's work in the 1860s established that acetification is the work of living bacteria rather than a spontaneous chemical change — an explanation this entry gropes toward without quite having.