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Vinegar, Colourless
To render pickling vinegar colourless, which it should be for some sorts of pickles, stir together one gallon of the best pickling vinegar and six ounces of bone black (animal charcoal); let the mixture stand for two or three days, then pour off the clear vinegar.
This is a purification step rather than a dish: it strips the brown of malt vinegar so that pale pickles stay pale. Distilled white vinegar has made it largely unnecessary, but the method still works if you want to decolourise a flavoured or homemade vinegar.
- The point of the exerciseColour, not flavour, is what is being removed. Cauliflower, silverskin onions and white cabbage pickled in brown malt vinegar turn a dull tan, which Victorian cooks considered a fault.
- Bone blackAlso called animal charcoal or bone char, made by calcining bones; it was the standard decolourising agent of the nineteenth-century sugar refinery. If you attempt this, use food-grade activated carbon. The bone black and lamp black sold as artists' pigments or industrial filter media are not intended for contact with food.
- The gallonCassell's is a British book, so this is an imperial gallon, 160 fl oz or about 4.5 litres. Six ounces of carbon to that volume works out at roughly 40 g per litre, which is a heavy dose by modern standards.
- Pouring off is not enoughDecanting leaves fine carbon in suspension. Strain the vinegar through a coffee filter or fine paper filter until it runs clear, or it will grey the pickle jar.
- Agitate, then let it settleStir the mixture once or twice a day over the two or three days, then leave it undisturbed for several hours before drawing off so the carbon beds down.
- Flavour is stripped tooActivated carbon takes out aroma compounds along with colour, so the finished vinegar is flatter than it started. Compensate with the spices in the pickling recipe rather than expecting the vinegar to carry the dish.
- AcidityDecolourising does not appreciably change acetic acid content, but pickling vinegar needs to be at least 5 per cent acetic acid to be safe for preserving. Check the label of whatever you begin with.
- The simpler modern routeBuy distilled white vinegar or a white wine vinegar at 5 to 6 per cent. It is colourless from the outset and costs less than the carbon.
In Victorian Britain pickling vinegar usually meant malt vinegar, brewed from barley and a deep amber brown, since cheap distilled white vinegar was not the household staple it is now. That left a problem of appearance: the pale pickles of the period, cauliflower and silverskin onions among them, looked muddy in a brown liquor. Bone char had been used from the early nineteenth century to decolourise cane sugar syrup, and its use here applies a refinery material to a domestic purpose. The entry is a preparatory process rather than a dish.