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Vinegar, Pickles, and Pickling: German
Air is admitted through the bung of the casks or otherwise, and the liquid is allowed to stand until it turns to vinegar. This takes two weeks or more in summer, and a month or more in cold weather. The process is similar to that of making cheap vinegar from molasses and yeast, or making ordinary cider vinegar. Or to make vinegar by the quick, or German process, prepare a special contrivance as follows:
Supply a large vinegar cask with a false bottom about a foot from the true bottom perforated with a large number of inch gimlet holes.
If a fine quality of vinegar is desired, cover this with one or more thicknesses of white flannel cloth, and an inch layer of clean white sand on top.
This is a fragment of a longer discussion of vinegar-making, and what it describes is a piece of equipment rather than a measured formula: the trickling generator that let nineteenth-century makers convert alcohol to acetic acid in days instead of months. A few things need translating before any of it makes sense at a modern bench.
- The bungThe bung is the stopper in the large hole in a cask's side. "Air is admitted through the bung" means loosening or replacing it with a cloth plug or vented spile so oxygen can reach the liquid, since acetic fermentation is aerobic and a sealed cask simply goes stale.
- The German or quick processWhat the book calls the quick process is the trickling or generator method: alcoholic liquid is poured over a deep bed of porous packing while air rises through it from below, so the bacteria work on a huge wetted surface. The slow method described in the first sentences is the same chemistry with only the surface of the liquid exposed, which is why it takes weeks or months.
- Inch gimlet holesA gimlet is a small hand boring tool; "inch gimlet holes" means holes bored roughly an inch across, and the book calls for a large number of them over the false bottom. They let air pass freely into the space above while the false bottom supports what is laid on it, and liquid drains back through them.
- Flannel and sandThe flannel and the inch of washed sand are a filter bed, meant to catch suspended matter and yeast so the vinegar runs bright. Beech shavings, corncobs or charcoal were the usual packing in the working part of the generator above; the passage as printed does not describe filling that space.
- What is missingNo strength of starting liquid, no quantity, no temperature and no acidity target is given here. A generator needs a dilute alcoholic wash, not spirits at full strength, and the bacteria are effectively inactive below about 60F and killed well short of boiling. Use a current, measured vinegar procedure for the actual fermentation.
- MaterialsWood, glass, food-grade plastic and stainless steel only. Vinegar will attack aluminium, copper, galvanised metal and cast iron, and a cask that has held anything other than food is not usable.
- Strength and keepingHome-made vinegar of unknown acidity should be treated as a table condiment, not a preservative. Pickling and canning recipes assume 5 percent acetic acid, and there is no way to judge that by taste.
- TimingThe two weeks to a month quoted for the slow method is realistic for a warm cask with a healthy mother. A generator can cut that to a few days, but only once the packing has been colonised, which itself takes weeks.
Vinegar was for centuries made by the slow surface method the passage opens with, the so-called Orleans process, in which part-filled casks of wine or cider stood vented in a warm room for months while a leathery mat of bacteria formed on top. The quick or German process is generally traced to Karl Sebastian Schuetzenbach in Baden in the 1820s, and it spread rapidly because a tall cask packed with beech shavings did in days what a cellar of casks did in a season. The microbial explanation was argued over for decades and is usually credited to Pasteur's work in the 1860s, which established acetic acid bacteria as the agent, and this is exactly the sort of half-explained industrial shortcut that household compendia of the following decades liked to pass along to readers with a barrel and a barn. That this book prints it in a chapter on pickling is telling: before commercial vinegar was cheap and standardised, a household that put up quantities of cucumbers and onions had a real interest in making its own sour liquor from cider, molasses or the leavings of the fruit press.