Acetic acid us lipid soluble and able to rapidly diffuse through the plasma membrane, a factor that has a dramatic effect on the pH of a cell.
Acetic acid is a natural metabolite in human metabolism and because it has been used in food preservation for thousands of years, it is not classified as a food preservative in EU Directive.
The acetic acid of the vinegar the preservative agent. Vinegar is formed by acetic acid fermentation of alcoholic liquids. The acetic acid formed will preserve the liquid, provided air is excluded after vinegar fermentation is over.
Vinegar normally is used as a preservative in pickling relishes and other foods that have been heated.
As little as 0.1% of the undissociated acid will inhibit the growth of most food poisoning and spore-forming bacteria and 0.3% will prevent the growth of mycotoxigenic moulds.
In vinegar preserves the effect of the acetic acid is frequently enhanced by the presence of salt.
