Vinegar is produced by an alcoholic fermentation of sugar-containing plant extracts followed by a microbial oxidation of ethanol to acetic acid. Vinegar is part of the cultural heritage of mankind and was developed during the agricultural revolution starting about 10 000 years ago in the Middle East. As early as 3000 BC, vinegar, manufactured by spontaneous fermentation of dates in Mesopotamian households, was used as a condiment and for food preservation. A review of the history and development, aswell as a bibliography of the raw materials used in vinegar making, was produced by Conner and Allgeier (1976) and by Adams (1985). Specific vinegars like spirit, wine, cider, malt, whey or rice vinegar take their names from the fermented raw materials.The antimicrobial activity of acetic acid is not simply a pH effect. The undissociated (lipophilic) molecule can penetrate the cell membrane, disrupting membrane transport processes and dissociating within the cell to increase acidity to produce toxic levels of the anion. The dissociation constant pK_a of acetic acid is 4 75. Below pH 3-5 more than 95% of the acetic acid is in the undissociated form (Adams 1985).
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