Vinegar (from Old French vinaigre, meaning "sour wine") is a sour-tasting liquid made from the oxidation of ethanol in wine, cider, beer, fermented fruit juice, or nearly any other liquid containing alcohol. It can also be made by certain bacteria operating on sugar-water solutions directly, without intermediary conversion to ethanol (see acetic acid). Commercially available vinegar usually has a pH of about 2.4.
Any type of vinegar may be distilled to produce a colourless solution of about 5% to 8% acetic acid in water. This is variously known as distilled, spirit or white vinegar, and is used for medicinal, laboratory and cleaning purposes as well as in cooking, including pickling. The most common starting material, due to its low cost, is malt vinegar.
The term 'spirit vinegar' is sometimes reserved for the stronger variety (5% to 20% acetic acid) made from sugar cane or from chemically produced acetic acid.
Malt vinegar is made by malting barley, causing the starch in the grain to turn to maltose. Then an ale is brewed from the maltose and allowed to turn into vinegar, which is then aged. It typically is light brown in color.
Balsamic vinegar is an aromatic, aged type of vinegar traditionally crafted in the Modena and Reggio Emilia provinces of Italy from the concentrated juice, or must, of white grapes (typically of the Trebbiano variety). It is very dark brown in color and its flavor is rich, sweet, and complex, with the finest grades being the product of years of aging in a successive number of casks made of various types of wood (including oak, mulberry, chestnut, cherry, juniper, ash, and acacia). Originally a product available only to the Italian upper classes, a cheaper form of balsamic vinegar became widely known and available around the world in the late twentieth century. True balsamic vinegar (which has Protected Designation of Origin) is aged for 12 to 25 years. Balsamic vinegars that have been aged for up to 100 years are available, though they are usually very expensive. The commercial balsamic sold in supermarkets is typically made with concentrated grape juice mixed with a strong vinegar, which is laced with caramel and sugar. Regardless of how it is produced, balsamic vinegar must be made from a grape product.
Balsamic vinegar has a high acidity level but the tart flavor is usually hidden by the sweetness of the other ingredients, making it very mellow.
Wine vinegar is made from red or white wine and is the most commonly used vinegar in Mediterranean countries and Central Europe. As with wine, there is a considerable range in quality. Better quality wine vinegars are matured in wood for up to two years and exhibit a complex, mellow flavor. Wine vinegar tends to have a lower acidity than that of white or cider vinegars. There are more expensive wine vinegars that are made from individual varieties of wine, such as Champagne, Sherry, or pinot grigio.
Rice vinegar, also sometimes called "rice wine vinegar", is a vinegar made from fermented rice or rice wine in China and Japan. Japanese rice vinegar is very mild and mellow and ranges in colour from colourless to pale yellow. There are two distinct types of Japanese vinegar: one is made from fermented rice and the other is made by adding rice vinegar to sake. Chinese rice vinegars are stronger than Japanese ones, and range in colour from clear to various shades of red and brown. Chinese and especially Japanese vinegars are very mild and sweet compared to more acidic Western vinegars which, for that reason, are not appropriate substitutes for rice vinegars.
Popular fruit-flavored vinegars include those infused with whole raspberries, blueberries, or figs (or else from flavorings derived from these fruits). Some of the more exotic fruit-flavored vinegars include blood orange and pear.
Herb vinegars are flavored with herbs, most commonly Mediterranean herbs such as thyme or oregano. Such vinegars can be prepared at home by adding sprigs of fresh or dried herbs to vinegar purchased at a grocery store; generally a light-colored, mild tasting vinegar, such as that made from white wine, is used for this purpose.
Sweetened vinegar is of Cantonese origin and is made from rice wine, sugar and herbs including ginger, cloves, and other spices.
Spiced vinegar, from the Philippines (labeled as spiced sukang maasim), is flavored with chili peppers, onions, and garlic.