In one of its most common forms, vinegar has been used as a
preservative since ancient times.
Vinegar can be made from any liquid that is capable of being
converted into alcohol in a two stage process. During fermentation
the sugar in the liquid is converted into alcohol and carbon
dioxide gas by the actions of yeast enzymes. Then, the alcohol
combines with atmospheric oxygen by the action of the Acetobacter
bacteria, forming acetic acid and water.
It is because of the variety of source materials, and the differing
organic acids and esters derived from that source material which
are also present, that are responsible for the different flavours
and aromas of vinegar, for example, grapes - wine vinegar, apples
- cider vinegar, malted barley or oats - malt vinegar.
In addition to the method for producing vinegar, large amounts
of acetic acid are prepared synthetically either by acetylene
being hydrated to acetaldehyde, which is then oxidized or by
a process using methanol, from gas or oil, and carbon monoxide.
In foods it is used for its antibacterial properties, as an
acidity stabiliser, diluting colourings, as a flavouring agent
and for inhibiting mould growth in bread. In brewing it is used
to reduce excess losses of carbohydrate from the germinated
barley and to compensate for production variations, so producing
a consistent quality beer.
It can be found in beer, bread, cheese, chutney, horseradish
cream, pickles, salad cream, brown sauce, fruit sauce, mint
sauce and jelly and tinned baby food, sardines and tomatoes.
Occurring naturally in body fluids and plant juices acetic
acid, also called ethanoic acid, is the most important of the
carboxylic acids. It is an important metabolic intermediate
being involved in fatty acid and carbohydrate metabolism.
of serrano ham and Spanish foods.