How Much do You Know About Vinegar?

I’m pretty sure almost every household have at least a bottle of vinegar at home. We often use vinegar in our daily life, but how much did you know about vinegar? Do you know how vinegar is made? Do you know what vinegar is made of? What is the application of vinegar?

Vinegar is a versatile liquid that is created from the fermentation of ethanol. The key ingredient is acetic acid, which has a distinctive sour taste and pungent smell. The typical pH of vinegar ranges is from 2 to 3.5, although the store-bought kind usually measures 2.4. In food preparation procedures, it is a multipurpose product as an ingredient or a condiment. Besides cooking, vinegar also has medicinal, household cleaning, and agricultural applications.

Acetic acid also known  as ethanoic acid is an organic compound with the formula CH₃COOH. Acetic acid is a carboxylic acid, thus it contan carboxyl group (–COOH) as the functional group. Acetic acid is a a weak acid, in that it is only a partially dissociated acid in an aqueous solution. Besides making of vinegar, acetic acid is also used in the manufacture of acetone and esters used in perfumes, the preparation of dyes, to coaggulate rubber from latex and for making white lead which is used as a white paint. The figure below shows the structure of acetic acid :

Acetic acid is formed in a four-step reaction know as alcholic fermentation. Alcoholic Fermentation, also referred to as ethanol fermentation, is a biological process in which sugars such as glucose, fructose, and sucrose are converted into cellular energy and thereby produce ethanol and carbon dioxide as metabolic waste products. Because yeasts perform this conversion in the absence of oxygen, alcoholic fermentation is considered an anaerobic process. Alcoholic Fermentation involving conversion of starch to sugar by amylases, anaerobic conversion of sugars to ethanol by yeast fermentation, conversion of ethanol to hydrated acetaldehyde, and also dehydrogenation to acetic acid by aldehyde dehydrogenase. The last two steps are performed aerobically with the aid of acetic acid forming bacteria. Acetic acid yield from fermented sugar is approximately 40%, with the remaining sugar metabolites either lost to volatilization or converted into other compounds. Acid yield improvements can be achieved using high rates aeration of during continuous production.

The making of vinegar involve two processes of fermentation that differ by speed of production. The fast fermentation process takes only few hours or few days but it requires the use of machinery to promote the oxygenation. The slow fermentation process takes weeks to months and it occurs naturally. At the same time, a nontoxic slime called mother of vinegar accumulates in the liquid. Composed of acetic acid bacteria and cellulose, mother is also available in stores and consumed by some despite its unappetizing appearance. Another part of the fermenting vinegar may include the non-parasitic nematodes called vinegar eels, which are free-living creatures that feed on the mother. While they are shown to be harmless to humans, manufacturers still filter them out of the product before bottling it.

There are many different types of vinegar, depending on what liquid the ethanol has been fermented in. For example, what is commonly known as white vinegar is brewed through oxidizing a distilled alcohol. Apple cider vinegar is made from apple, which is the freshly pressed apple with its various solid components, and sold unfiltered. Similarly, the aromatic balsamic vinegar is made from the white grapes. Traditionally brewed in Italy, authentically aged balsamic is very expensive; the inexpensive store-bought varieties that are more common are made with a strong vinegar combined with natural flavors and sugars. In other parts of the world, vinegar is also derived from raisins, cane, coconut, rice, dates, and even honey.