Vinegar

Vinegar is sometimes infused with spices or herbs; here, it is flavored with oregano.

Vinegar is a sour liquid produced from the fermentation of diluted alcohol products to yield the organic compound acetic acid, its key ingredient. Used in many cultures as a condiment and preservative, vinegar can be made from a variety of liquids, including malted barley, rice, and cider; however, as its name suggests, it was probably first made from wine. (The word vinegar derives from the Old French vinaigre, meaning "sour wine.")

Crucially, vinegar must be derived from a sugar-containing source in a two-step process. In the first stage, the sugars are broken down in the absence of oxygen (i.e., fermented) by yeast to produce alcohol (ethanol) and carbon dioxide. In the second stage, the addition of oxygen enables bacteria to produce amino acid, water, and other compounds. Thus, the British alternative to malt vinegar, called non-brewed condiment, does not qualify as vinegar because its acetic acid component is obtained directly by distilling wood chips, bypassing the first, ethanol-producing stage.

Though commercial production of vinegar continues to involve the natural action of bacteria, industrial production accelerates the process, primarily through mechanisms that increase the supply of oxygen (necessary for the conversion of ethanol into acetic acid) to the bacteria. High-quality vinegars, such as balsamic vinegars prepared in Modena, Italy, continue to be produced via a slow process of fermentation, typically aging in wood barrels for a period of 3-12 years.

Vinegar is as old as civilization itself: traces of it have been found in Egyptian urns from around 3000 B.C.E., and Babylonian scrolls recording the use of vinegar date even earlier, to around 5000 B.C.E. Known as “poor man’s wine” (posca) in Biblical times, vinegar was often carried by Roman legionnaires; four Biblical passages note that Roman soldiers offered vinegar to Christ at the Crucifixion.

Today, vinegar remains an important element in European, Asian, and other traditional cuisines of the world; it is often used in pickling and in the creation of marinades, dressings, and other sauces. It also functions as a folk remedy in many cultures and as a natural household cleaning product and herbicide.

Components and properties

A three-dimensional model of acetic acid, the key component of vinegar.

Acetic acid, also known as ethanoic acid, is an organic chemical compound with the formula CH₃COOH. It is one of the simplest carboxylic acids. Though carboxylic acids are weak acids, they are stronger than the alcohols (-OH) from which they are derived, in part as a result of the electron-withdrawing power of their second oxygen atom. (The greater number of oxygen atoms attached, the stronger the acid.)

The acetic acid concentration in vinegar typically ranges from 4 to 8 percent by volume for table vinegar, though higher concentrations are found in vinegars used for pickling (up to 18%). Natural vinegars also contain smaller amounts of tartaric acid, citric acid, and other acids.

Acetic acid gives vinegar its characteristic sour taste and pungent smell. It also accounts for vinegar’s chemical properties. The pH of vinegar is typically in the range of 2 to 3.5, depending on the concentration of acetic acid. Commercially available vinegar usually has a pH of about 2.4. Vinegar has a density of approximately 0.96 g/mL, depending on the acidity of the vinegar.

Commercial production

Acetic acid is produced both synthetically and by bacterial fermentation. Today, the biological route accounts for only about 10% of world production, but it remains important for vinegar production, as many of the world food purity laws stipulate that vinegar used in foods must be of biological origin.

For most of human history, acetic acid has been made from fermented liquids by acetic acid bacteria of the genus Acetobacter. However, their function was not understood until Louis Pasteur discussed the microbiological basis of vinegar in his 1858 work Etudes sur le Vinaigre (which was updated in 1864 as Memoirs sur la Fermentation Acetic).

Given sufficient oxygen, these bacteria can produce vinegar from a variety of alcoholic foodstuffs. Commonly used feeds include apple cider, wine, and fermented grain, malt, rice, or potato mashes. The overall chemical reaction facilitated by these bacteria can be summarized as follows:

C₂H₅OH + O₂ → CH₃COOH + H₂O

A dilute alcohol solution inoculated with acetobacter and kept in a warm, airy place will become vinegar over the course of a few months. Industrial vinegar-making methods accelerate this process by improving the supply of oxygen to the bacteria.

Barrels of balsamic vinegar aging in a maker's attic, an example of the slow method of fermentation.

The first batches of vinegar produced by fermentation probably resulted from errors in the winemaking process. If must is fermented at an overly high temperature, acetobacter will overwhelm the yeast naturally occurring on the grapes. As the demand for vinegar for culinary, medical, and sanitary purposes increased, vintners quickly learned to use other organic materials to produce vinegar in the hot summer months before the grapes were ripe and ready for processing into wine.

According to the Orleans process (named after a town in France where high-quality vinegar is still produced today), vinegar is made in fifty-gallon barrels packed with an oxygenating substance, such as chips of wood. When it reaches the desired degree of acidity, the vinegar is transferred to an aging barrel and left to mature to a mellow smoothness.

One of the first modern commercial processes was the fast method or German method, first practiced in Germany in 1823. In this process, fermentation takes place in a tower packed with wood shavings, corncobs, or charcoal. The alcohol-containing feed is trickled into the top of the tower, and fresh air is supplied from the bottom by either natural or forced convection. The improved air supply in this process cut the time to prepare vinegar from months to weeks.

Most vinegar today is made in submerged tank culture, first described in 1949 by Otto Hromatka and Heinrich Ebner. In this method, alcohol is fermented to vinegar in a continuously stirred tank, and oxygen is supplied by bubbling air through the solution. Using this method, vinegar of 15% acetic acid can be prepared in only 2–3 days.

The longer fermentation period allows for the accumulation of a nontoxic slime known as the mother of vinegar, a mixture of acetic acid bacteria and soluble cellulose. (In industrial fermentation, a madmade mother of vinegar called Acetozym is added as a nutrient.) As with wine, the aging process also generates a complexity and depth of flavor lacking in newly brewed vinegar, which tends to be sharp and harsh in taste.

Types of vinegar

Vinegar can be made from any carbohydrate-containing liquid capable of being converted into alcohol, hence, the diversity of materials:

Apple cider vinegar

Apple cider vinegar, otherwise known simply as cider vinegar, is made from cider or apple must, and is often sold unfiltered, with a brownish-yellow color.

Balsamic vinegar

Balsamic vinegar is an aromatic vinegar manufactured from the concentrated must of white grapes (typically of the Trebbiano variety), which is then fermented via a slow aging process that concentrates the flavors. The flavor intensifies over decades, as the vinegar is kept in fine wooden casks, becoming sweet, viscous and very concentrated. Balsamic has a high acid level, but the sweetness covers the tartness, making it very mellow in flavor. 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 finest and most traditional balsamic vinegar, manufactured in Modena, Italy, is very labor-intensive to produce; while it ages and gradually evaporates, the liquid is transferred to successively smaller casks made of different woods, absorbing the flavour characteristics of each wood and becoming more concentrated with each transfer. Oak, mulberry, chestnut, cherry, juniper, ash, and acacia are the most commonly used woods.[1] Some older balsamic vinegar is added to the must to create a more complex and intricate taste, and to enhance acidity. At the end of the process, the vinegar is taken from the smallest cask: each cask is filled with the contents of the preceding (larger) cask and the cooked must is added to the largest cask.

The commercial balsamic sold in supermarkets is typically made with red wine vinegar or concentrated grape juice mixed with a strong vinegar which is laced with caramel and sugar. However produced, balsamic vinegar must be made from a grape product.

Malt vinegar

Malt vinegar is made by malting barley, causing the starch in the grain to turn to maltose. An ale is then brewed from the maltose and allowed to turn into vinegar, which is then aged. Malt vinegar is typically light brown in color. It is especially popular as a condiment for the traditional pub fare of fish and chips in England.

Rice vinegars

Rice vinegar is most popular in the cuisines of East and Southeast Asia. It is available in white (actually light yellow), red, and black variants. The Japanese prefer a light and more delicate rice vinegar for the preparation of sushi rice and salad dressings. Red rice vinegar is traditionally colored with red yeast rice, although some Chinese brands use artificial food coloring instead.[2]. Black rice vinegar (made with black glutinous rice) is most popular in China, although it is also produced in Japan.

Because rice vinegar typically has a bland flavor, some varieties are sweetened or otherwise seasoned with spices or other added flavorings.

Chinese black vinegar is an aged product made from rice, wheat, millet, or sorghum, or a combination thereof. It has an inky black color and a complex, malty flavor.[3] A somewhat lighter form of black vinegar, made from rice, is also produced in Japan, where it is called kurozu.

White vinegar

White vinegar, which is actually transparent in appearance, is an example of a distilled vinegar. In the distilling process, the vinegar is first turned into steam using high heat, then allowed to condense back into liquid form. This process destroys many of the nutrients present in the undistilled vinegar, resulting in a vinegar that is almost pure acetic acid. Most commercial white vinegars are 5% acetic acid solutions, and are made from grain (often maize) and water. White vinegar is used for culinary as well as cleaning purposes; it is a good choice for pickling because it will not alter the color of the vegetable being preserved.

Wine vinegars

Wine vinegar, made from red or white wine, is the most commonly used vinegar in the cuisines of the 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 less acidity than that of white or cider vinegars. There are also wine vinegars made from individual grape varieties, such as Champagne, Sherry, or pinot grigio.

Other types of vinegar

• Coconut vinegar, made from the sap, or "toddy," of the coconut palm, is used extensively in Southeast Asian cuisine (particularly in the Philippines, which is a major producer), 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 Ilocos Region of the northern 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. In the Philippines, it is often labeled as sukang maasim, although this is simply a generic term meaning "sour vinegar."
• Fruit vinegars are made from fruit wines usually without any additional flavoring. Common flavors of fruit vinegar include apple, black currant, raspberry, quince, and tomato. Most fruit 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, and jujube vinegar is produced in China.
• Raisin and date vinegars are used in cuisines of the Middle East.
• Vinegar made from honey is rare, though commercially available honey vinegars are produced in Italy and France.
• Kombucha vinegar is made from kombucha, a symbiotic culture of yeast and bacteria. The bacteria produce a complex array of nutrients and populate the vinegar with symbiotic bacteria that promote a healthy digestive tract. Kombucha vinegar is primarily used to make a vinaigrette and flavored by adding strawberries, blackberries, mint, or blueberries at the beginning of fermentation.

Flavored 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 store-bought vinegar; generally a light-colored, mild-tasting vinegar such as that made from white wine is used for this purpose.

Sweetened vinegar 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.

Uses

Culinary uses

Vinegar is commonly used in food preparation, particularly in pickling processes, vinaigrettes, and other salad dressings. It is an ingredient in condiments such as mustard, ketchup, and mayonnaise. Vinegar is an essential component of chutneys, marinades, and other sauces.

Uses in alternative medicine

Various folk remedies and treatments have been ascribed to vinegar over millennia in cultures worldwide. The ancient Greek physician Hippocrates (ca. 460 B.C.E. – ca. 370 B.C.E.), for example, prescribed vinegar for many ailments, from skin rash to ear infection. And the therapeutic use of vinegar for the treatment of headaches 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.” Other – include:

• Treatment for jellyfish stings Applying vinegar to jellyfish stings deactivates the nematocysts.
• Apple cider vinegar is a much more useful astringent than ice and will reduce inflammation, bruising and swelling in approximately a third of the time that ice will take.
• Claims that cider vinegar can be used as a beauty aid also persist, it is a powerful remedy for Acne skin conditions when diluted 50:50 with water and used as a toner. The British Romantic poet Lord Byron, for example, would consume vast quantities of white vinegar in an attempt to keep his complexion pale.
• 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.
• Vinegar is also used to cure mild to moderate sunburn when soaked on the area with a towel or in a bath.
• Cider vinegar is a natural remedy for yeast infections, when diluted with water and used as a douche.

Though few of the remedies above have been verifiable using controlled medical trials, clinical trials have revealed that small amounts of vinegar (approx. 20 mls or two tablespoons of domestic vinegar) added to food, or taken along with a meal, reduce the glycemic index of carbohydrate-rich foods in both healthy and diabetic recipients. This has also been expressed as lower glycemic index ratings in the region of 30%.

Multiple trials indicate that taking vinegar with food increases satiety (the feeling of fullness) and so reduces the amount of food consumed. Even a single application of vinegar can lead to reduced food intake for a whole day.

Use as a household cleaner

White vinegar, diluted with water, is often used as a natural household cleaning agent. It is especially useful for cleaning mineral deposits on glass and other smooth surfaces. Care should be taken to not allow contact with eyes (if such contact occurs, the eyes should be flushed immediately and persistently with warm water) or skin (the affected skin area should be washed thoroughly after use).

Agricultural and horticultural uses

Vinegar can be used as a herbicide as shown by scientific trials reported by the US Dept of Agriculture in 2002. Vinegar made from natural products classifies as organic and so there is interest in it being used on farms/orchards/gardens certified as organic. The trials showed that a number of common weeds could be effectively controlled using vinegar with 5% to 20% acetic acid. Lower concentrations are less effective. A crop of corn can be sprayed with vinegar at 20% strength without causing harm to that crop, and so it can be used to help keep a corn crop clear of weeds. Acetic acid is not absorbed into root systems and so vinegar will kill top growth but perennial plants will reshoot.

References

ISBN links support NWE through referral fees

• Antol, M.N. 2000. The Incredible Secrets of Vinegar. New York: Avery Publishing Group.
• Atkins, P., and L. Jones. 2005. Chemical Principles, 3rd edition. New York: W. H. Freeman.

External links

• [4] - Apple Cider Vinegar Cure Research- Page 2
• [5] - Apple Cider Vinegar Cure Research - Page 1
• The Vinegar Institute - Promotional website from members of the vinegar industry
• Acetic Acid
• Vinegar: Medicinal Uses and Antiglycemic Effect - Medscape.com article by Carol S. Johnston, PhD, RD and Cindy A. Gaas, BS.
• Vinegar Connoisseurs International
• Information about production and uses
• Weird Facts - 50 Uses for Vinegar
• Apple Vinegar- Therapeutical properties.

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