Vinegar, that sour-tasting kitchen staple named after the French vin aigre for "wine sour", is also a chemical, a dilute form of acetic acid. Made the world over since ancient times, vinegar is used in both Western and Asian cuisines. Most vinegars are from three to five percent acetic acid by volume - the more dilute forms are used for table vinegar and the higher concentrations for pickling. Natural vinegars also contain small amounts of tartaric acid, citric acid, and other acids besides acetic. These acids come from the breakdown of some of the sugars that exist in the fruit used to make vinegar; malic acid, for example, is a product of the xxx in apples, and is a component of many apple cider vinegars. There are other ingredients,like berries, herbs, or spices, that are sometimes added for flavoring, after the vinegar is distilled.
Vinegar has traditionally been made by the oxidation of ethanol, the organic alcohol found in wine, cider, beer, fermented fruit juice, and other alcoholic drinks. Ethanol itself is made by the oxidation of sugars. Although vinegar can be made by certain bacteria operating on sugar-water solutions directly, without intermediary conversion to ethanol (see acetic acid), the traditional vinegars used in cooking are all made from fermention of sugary foods to ethanol. Sugar-containing substances, like apple cider or grape juice, are allowed to ferment into an alcoholic solution containing ethanol, like hard cider or wine, and then further oxidized into vinegar. Since the very portion of the ethanol molecule that makes it an alcohol is the part that is changed into an acid with oxidation, vinegar is non-alcoholic. Although all vinegars contain acetic acid, there are differences between different types of vinegars. Just as the proof of an alcoholic beverage containing ethanol is based on the concentration of alcohol, the acidity of vinegar varies according to the concentration of acetic acid in each sort of vinegar. There are other important differences, besides taste and the ability to intoxicate, between ethanol and vinegar. Whereas even pure ethanol can be drunk in small quantities by a human without damaging the mouth or throat, very concentrated acetic acid is a caustic material that causes serious burns if it touches the lips, or the lining of the mouth and throat. Food quality acetic acid is never in such a concentrated form. The actual concentration of acetic acid in different types of vinegars is variable, and depends on just how the vinegar was made, but generally, the acidity measured by pH is between 2.4 and 5. The closer the pH is to 1, the more acid the solution.
The color and taste of vinegar varies according to other ingredients in the solution besides acetic acid and water. Red wine vinegar, for example, retains the color of the red grape pigments and has a certain flavor from ingredients other than acetic acid. Many forms of "white vinegar" are made from sources that do not impart pigments, and so the vinegar is clear. Although some white vinegars are made from fermented fruits, an appropriately dilute solution of the chemical acetic acid is a white vinegar. This inexpensive form is sometimes used as a cleaning agent.
Vinegar production may be started by the addition of mother of vinegar to wine or cider. The oxidation is carried out by acetic acid bacteria, as was shown in 1864 by Louis Pasteur. Modern systems work with vinegar bacteria at the liquid and bring air into the vinegar with a venturi pump system or with a turbine. These systems have a production time between 38 hours and three days to get the ready vinegar.
Types of vinegar
Vinegars are usually made from a fruit or grain that is locally plentiful. The specific vinegars used in regional cooking vary accordingly.
A cheaper alternative, called "non-brewed condiment," is a solution of 4-8% acetic acid colored with caramel. There is also around 1-3% citric acid present. Non-brewed condiment is more popular in the North of England, and gained popularity with the rise of the Temperance Societies. The non-alcoholic nature of non-brewed condiment therefore makes it popular for individuals whose cultural or religious beliefs forbid them from drinking alcohol.
Wine vinegar is made from red or white wine, and is the most commonly used vinegar in Mediterranean countries, Germany, and other countries. 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. There are more expensive wine vinegars made from individual varieties of wine, such as Champagne vinegar and sherry vinegar.
Apple cider vinegar, sometimes known simply as cider vinegar, is made from cider or apple must, and is often sold unfiltered, with a brownish-yellow color; it often contains mother of vinegar. It is currently very popular, partly due to its alleged beneficial health and beauty properties (see below). Some countries, like Canada, prohibit the selling of vinegar over a certain percentage acidity.
In terms of cooking, cider vinegar is not usually suitable for use in delicate sauces, but is excellent for use in chutneys and marinades. It is used to make vinegar pie and can also be used to pickle foods, but will darken light fruits and vegetables.
Fruit vinegars are made from fruit wines without any additional flavouring. Common flavors of fruit vinegar include black currant, raspberry, and quince. Typically, the flavors of the original fruits remain tasteable in the final vinegar.
Most such vinegars are produced in Europe, where there is a growing market for high price vinegars made solely from specific fruits (as opposed to non-fruit vinegars which are infused with fruits or fruit flavors. Persimmon vinegar is popular in South Korea.
Balsamic vinegar is an aromatic, aged type of vinegar manufactured in Modena, Italy, from the concentrated juice, or must, of white grapes (typically of the Trebbiano variety). Its flavor is rich, sweet, and complex, with the finest grades being the end 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 an artisanal product available only to the Italian upper classes, balsamic vinegar became widely known and available around the world in the late 20th century.
The Japanese prefer a more delicate rice vinegar and use it for much the same purposes as Europeans, as well as for sushi rice, in which it is an essential ingredient. Rice vinegar is available in white, red, and black variants, the last of which is most popular in China (see Chinese black, below). Black rice vinegar may be used as a substitute for balsamic vinegar, though its dark color and the fact that it is aged may be the only similarity between the two products. Some types of rice vinegar are sweetened or otherwise seasoned.
Coconut vinegar, made from the sap, or "toddy," of the coconut palm, is used extensively in Southeast Asian cuisine (particularly in the Philippines, a major producer of the product), as well as in some cuisines of India. A cloudy white liquid, it has a particularly sharp, acidic taste with a slightly yeasty note.
Cane vinegar, made from sugar cane juice, is most popular in the Philippines (where it is called sukang iloko), although it is also produced in France and the United States. It ranges from dark yellow to golden brown in color and has a mellow flavor, similar in some respects to rice vinegar, though with a somewhat "fresher" taste. Contrary to expectation, it is not sweeter than other vinegars, containing no residual sugar.
Vinegar made from raisins is used in cuisines of the Middle East, and is produced in Turkey. It is cloudy and medium brown in color, with a mild flavor.
Vinegar made from beer is produced in Germany, Austria, and the Netherlands. Although its flavor depends on the particular type of beer from which it is made, it is often described as having a malty taste. That produced in Bavaria is a light golden color, with a very sharp and not overly complex flavor.
Chinese black vinegar is an aged product made from rice, wheat, millet, or sorghum. It has an inky black color and a complex flavor. It is typically served as a dipping sauce with jiaozi (dumplings) to complement the fat of the dumplings' filling.
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 store-bought vinegar; generally a light-colored, mild tasting vinegar such as that made from white wine is used for this purpose.
An East Asian variety of flavored vinegar known as sweetened vinegar is made from rice wine and herbs including ginger, cloves and other spices. It is an integral ingredient in the traditional Chinese postnatal health and celebratory dish of Pork Knuckles and Ginger Stew .
Vinegar is commonly used in food preparation, particularly in pickling processes, vinaigrettes, and other salad dressings. It is an ingredient in sauces such as mustard, ketchup, and mayonnaise. It is also often used as a condiment.
Vinegar can be a potent, inexpensive and environment-friendly cleaning agent. White vinegar is generally recommended when vinegar is being used as a cleaning fluid. Do not use vinegar on plated surfaces as it may damage the plating.
- A few tablespoons of white vinegar mixed with a few teaspoons of common table salt makes an excellent cleanser for cleaning badly-stained stainless cookware. This vinegar and salt mixture can also remove oxidation from copper-clad cookware and make it shine with practically no rubbing required.
- One part white vinegar to four parts water (for a stronger solution, one part white vinegar to one part water works) makes a fine window-washing fluid, substituting for proprietary window cleaning fluids such as Windex and Windowlene. If windows appear streaky after washing with vinegar, add a small amount of liquid soap to the mix—this removes the residue of waxy streaks left over by commercial window cleaners. This same vinegar solution can also be used to clean some types of floors
- Drains can be cleaned by using a combination of vinegar and baking soda. Pour 100g baking soda down the drain, followed by 100ml of white vinegar. Let sit for a while. Cover the drain while it works, then pour a tea kettle full of boiling water down the drain. This is a good way to prevent build-up in the drain.
- Vinegar also works well as a fabric softener; just add 100ml to the rinse cycle.
- Add 200ml of vinegar to an empty dishwasher and run through the washing cycle to remove mineral deposits and odors. You can also put it in the rinse dispenser instead of proprietary rinse aid products.
- Removing odors using commercial cleaners often causes damage to surfaces. Vinegar can act as a very effective odor-remover especially in situations involving sensitive surfaces.
- Weak solutions of vinegar or acetic acid in water are used for douches.
- Vinegar can also be used as a solvent for removing the adhesive residue tapes leave on glass and plastic. It works well for quickly removing an adhesive residue that has been left on for about 1-2 weeks. To remove the adhesive residue using vinegar, you should:
- Apply the vinegar to a cloth or paper towel.
- Dab the cloth or paper towel in a little bit of vinegar.
- Scrub at the surface with the damp side of the cloth or paper towel.
- Dry the surface.
- Limescale deposits can be removed by vinegar. It's effective when used on scaled showerheads and around water taps. To remove limescale spots from water taps, moisten paper towels with un-diluted vinegar, wrap around the scaled taps and then cover with small bags (you may need to secure the bags with elastic bands). Leave for several hours or overnight, repeating if necessary. To remove limescale from a scaled showerhead, place the showerhead into a small bag, cover the scaled area with un-diluted vinegar and leave to soak overnight.
Medical and veterinary uses
The therapeutic use of vinegar is recorded in the second verse of the nursery rhyme "Jack and Jill": "Went to bed and bound his head / With vinegar and brown paper." As with some nursery rhymes, there is truth in the story. This one comes from the village of Kilmersdon in Somerset. The vinegar used would likely have been cider vinegar. Apple cider vinegar has been a folk remedy in the United States since settlement, and areas with populations that originally emigrated from Britain have been noted for the traditional medicinal use of apple cider vinegar. These areas include New England and Appalachia. In a survey of over 600 elderly residents of the Appalachian region, "cider vinegar made at home with Malus domestica' (domestic apples)', or purchased at stores, was the most frequently reported plant food medicine (n = 357). Informants reported its use for 36 disorders, but its primary uses were for sunburn, sprain, sore throat, indigestion, arthritis, and burn." (reference for quote: A. Cavender:Folk medical uses of plant foods in southern Appalachia, United States. Journal of Ethnopharmacology Volume 108, Issue 1 , 3 November 2006, Pages 74-84)
Vinegar along with hydrogen peroxide (H2O2) is used in the livestock industry to kill bacteria and viruses before refrigeration storage. A chemical mixture of peracetic acid is formed when acetic acid is mixed with hydrogen peroxide. It is being used in some Asian countries by aerosol sprays for control of pneumonia. A mixture of five-percent acetic acid and three-percent hydrogen peroxide is commonly used.
Apple cider vinegar in particular is often touted as a medical aid, from cancer prevention to alleviation of joint pain to weight loss.     These claims began in Biblical times; in 1958, Dr. D. C. Jarvis made the remedy popular with a book that sold 500,000 copies.
Claims that cider vinegar can be used as a beauty aid also persist,  despite the fact that apple cider vinegar can sometimes be very dangerous to the eyes. The acid will burn and the eyes will become red, but no damage to the eyes has ever been described. If the vinegar contains mother of vinegar the slime bacteria of the mother can cause ophthalmitis.
Many believe that vinegar is also a cure to mild to moderate sunburn when soaked on the area with a towel or in a bath.
Cider vinegar is also claimed to be a solution to dandruff, in that the acid in the vinegar kills the fungus Malassezia furfur (formerly known as Pityrosporum ovale) and restores the chemical balance of the skin.
Colic is a serious condition in horses that is more likely to affect those who have already survived an episode than those horses who have never had this intestinal crisis. "Apple cider vinegar supplementation to promote colonic acidification" is a standard crrent recommendation for high-risk horses. (reference for quote: D.C. Archer and C.J. Proudmana: Epidemiological clues to preventing colic.The Veterinary Journal. Volume 172, Issue 1 , July 2006, Pages 29-39)
- When vinegar is added to sodium bicarbonate (baking soda), it produces a very fizzy and volatile mixture of carbonic acid decomposing into carbon dioxide and water. It is exemplified as the typical acid-base reaction in school science experiments. The salt that is formed is sodium acetate.
- According to the Prophet Mohammed, vinegar is one of the best condiments (Ref. Sahih Muslim Book 023, Number 5091).
- Lord Byron would consume vast quantities of white vinegar to keep his complexion pale.
- Vinegar can also be used as an organic herbicide.
- List of uses of Vinegar from About.com (submitted by readers) http://frugalliving.about.com/cs/tips/a/vinclean.htm.