Bhat et al.

and then acetous”. The raw materials used for vinegar production include

rice, grapes, malt, apple, honey, potatoes, whey or any other sugary food

(Bamforth 2005). In human history, vinegar appears at the beginning

of agriculture with the discovery of alcoholic fermentation from fruits,

cereals and vegetables. The genesis of vinegar can hardly be distinguished

from the origin of wine. Although vinegar has always been considered

among the lowest quality products of fermented foods, it has also been

used as a food condiment, as a preservative agent and, in some countries

as a healthy drink (Solieri and Giudici, 2009).

Vinegarȱcontainsȱaboutȱ5%ȱaceticȱacidȱinȱwater,ȱvaryingȱamountsȱofȱfixedȱ

fruitȱacids,ȱcolouringȱmatter,ȱsaltsȱandȱaȱfewȱotherȱfermentationȱproductsȱ

whichȱimpartȱaȱcharacteristicȱflavourȱandȱaromaȱtoȱtheȱproduct.ȱ

Vinegar production

Vinegar is the product made from the conversion of ethyl alcohol to acetic

acid by a genus of bacteria, Acetobacter . Therefore, vinegar can be produced

from any alcoholic material from alcohol-water mixtures to various fruit

wines (Peppler and Beaman 1967). Vinegar bacteria, also called acetic acid

bacteria (AAB), are members of the genus Acetobacter and characterised by

their ability to convert ethyl alcohol (C ₂ H ₅ OH) into acetic acid(CH 3 COOH)

by oxidation as shown below:

Vinegar is a solution of acetic acid produced by a two-step bioprocess.

Inȱtheȱfirstȱstep,ȱfermentableȱsugarsȱareȱtransformedȱintoȱethanolȱbyȱtheȱ

action of yeast. In the second step, AAB oxidize the ethanol into acetic acid

in an aerobic process. AAB are well known for their ability to spoil wines

because they can produce large amounts of acetic acid from ethanol and

other compounds present in wines (Joyeux et al., 1984).

Substrates used in vinegar production

One of the critical steps in vinegar production is the preparation of the

raw material (Solieri and Giudici 2009). This step is required to obtain

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