The word vinegar comes from the French vin aigre meaning ‘sour wine’. There is also an old word ‘alegar’ or ‘algar’ meaning sour ale, now out of general use. Today, we call all such sour liquids vinegar, with a descriptive adjective; thus, wine vinegar, malt vinegar, cider vinegar and so on.
Vinegar has been used for at least five thousand years and probably for much longer, because it develops through an entirely natural process. Yeasts are always present in the air so, under natural conditions, a liquid containing sugar (such as fruit juice, malt liquor or honey water) will ferment with the formation of alcohol. Once alcohol has been formed, unless the liquid is closely corked, bacteria take over and oxidize the alcohol to acetic acid. The result is the sour liquid known as vinegar. The bacteria, in oxidizing the alcohol, use oxygen, which is why vinegar forms only from wine uncorked and exposed to the air.
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If vinegar is left opened, the acetic acid in it will, in turn, be attacked by microorganisms and further broken down, unless the concentration of acid is over a certain strength. Just as spirits or fortified wines will not sour, so also artificially strengthened vinegar will not deteriorate. Dilute vinegar may, so when making pickles of watery vegetables one must be sure to start with a really strong vinegar or extract some of the water first.
The strength of acetic acid in vinegar varies considerably. Wine vinegar is the strongest natural vinegar with about six and one half per cent acid; malt vinegar and cider vinegar are less strong with between four and five per cent acid. Distilled or fortified vinegars, on the other hand, go up to about twelve per cent.
Though acetic acid has some flavour as well as sourness, the special taste of good vinegars is due to small quantities of other substances, mainly volatile esters, having fruity or other interesting aromas. These substances are also present in the original wine (malt or cider) from which the vinegar was made, so good vinegar comes from good wine. The selection of a fine vinegar, especially for use in salads and delicate sauces, is very important and is frequently not given sufficient consideration.
Wine vinegar may be either white or red, being made from either white or red wine. In winegrowing countries, most vinegar is made from wine (or is claimed to be) and varies in quality. Because vinegar is wine vinegar, it is not necessarily good. In many places, it is customary for people
To make their own by pouring leftover wine into a bottle and leaving it till it turns sour. Sometimes such hit or miss methods make very good vinegar, but as often as not the result is rank and raw.
Commercial wine vinegar is made by dripping wine through open casks loosely filled with wicker work or wood shavings to provide plenty of surface. On this surface the wine and bacteria are exposed to the oxygen in the air. The bacteria proliferate, turn the alcohol to acetic acid, and during the process heat is produced; the faster the reaction goes, the hotter it gets. Heat tends to drive off the more delicate volatile aromas, and, therefore, fast vinegar processes, though cheaper to operate, produce inferior vinegars.
The superior vinegars are produced by the Orleans and Boerhaave slow processes. Oak vats with air holes at the top are kept half filled with wine and a film of the bacteria, known as ‘mother of vinegar’, forms on the top (this also contains tiny nematode worms which help in the process). The temperature is kept at about 70°F (21°C). The alcohol tends to move to the top of the cask and the acetic acid to the bottom, so that vinegar can be drawn weekly from the bottom and more wine added to replace it. The slow processes, cool and quiet, preserve in the vinegars the flavours of the wines from which they are made. Fine wine vinegars made by the slow processes are expensive, but a good wine vinegar is always worth paying for. It is far superior to lemon juice or malt vinegar as a dressing for salads and rarely causes digestive upsets, which lemon juice, though much publicized by health food experts, can do.
Malt vinegar. In England and northern Europe, vinegars are traditionally made from beer and are called malt vinegars. Malt, or malt and grain mixed together, is heated with water and then fermented to make a crude kind of beer known as ‘gyle’. Bacteria act on this alcoholic liquid as it drips through the vats filled with basket work or beech shavings. The malt vinegar, after being matured for several months, contains about six per cent acid and is then diluted to the strength required for sale. Malt vinegar is usually coloured and has quite a different flavour from wine vinegar. It is better for some purposes, for instance, in recipes for English pickles. For international cooking, one should keep several kinds of vinegar in the kitchen, using malt vinegar for recipes of English origin and wine vinegar for recipes from southern Europe, unless one is quite certain from personal experience that a change from tradition is preferable. One cannot say that one kind of vinegar is better than another, only that it is different.
Cider vinegar is made from cider and has a strong particular taste of its own. It is rather popular in America, but cannot be indiscriminately substituted for wine or malt vinegar. There is, however, quite a lot of evidence to suggest that cider vinegar is an exceedingly healthy substance in the diet. Cider vinegar in water is the basis of a whole school of naturalistic medicine which started in America and has spread elsewhere.
Distilled vinegars are popular in the north of England and in Scotland. (What Scotsman can resist distillation!) They are colourless and are made by carefully distilling natural vinegar in a vacuum Although much stronger than natural vinegar, some of the aroma of the original is retained. Because distilled vinegar is strong, it is useful for making pickles.
Spirit vinegar is made by distilling before all the alcohol has been converted to acetic acid. It therefore contains a small quantity of alcohol, which makes the flavour rather different.
Other vinegars can be made from mead, fruit wine or any fermented liquors. Vinegars rather
Naturally tend to follow the drink of the country in which they are made, and so in Japan and China one will find vinegar made from rice wine. Yamabukizu is a sweet-sour Japanese vinegar used for seasoning rice (substitute a small cup of white vinegar sweetened with three teaspoons of sugar). Another interesting vinegar is produced from wine made from the fruit of the cashew nut (Ill. Plate 17, No. 2).
Flavoured vinegars are often made with fruits, flower petals, herbs or spices. These may be made at home, but some are on sale in shops. Tarragon vinegar is the most usual. Herb vinegars are made simply by macerating the herb or spice in vinegar and, afterwards, straining if necessary.
Synthetic and inferior vinegars. There are some really nasty vinegars about. They may be made from synthetic acetic acid suitably diluted with water, either colourless or coloured with caramel.
More commonly, cheap vinegar is made by the natural process, but starting from cheap ingredients like wood pulp. Unless the product has been carefully purified, traces of harmful chemicals are possibly present, so cheap vinegars should be avoided not only for their poor flavour but also for reasons of health.