Vinegar is produced through a two- stage fermentation process, the first being the conversion of fermentable sugars into ethanol by yeasts, generally Saccharomyces species, and the second being the oxidation of ethanol by bacteria,generally Acetobacter species. Fermentation is a key process in the production of fruit vinegars, during which many volatile compounds, polyphenols, and organic acids, among others, are modified through chemical and microbial actions.