Acetic acid

The sharp-tasting organic acid that gives vinegar its bite, produced when acetic acid bacteria oxidise ethanol. Beyond vinegar itself, it is used as a preservative, acidity regulator and flavouring, and concentrated grades serve industry as a solvent and processing aid. Its antimicrobial power comes from the undissociated acid slipping through microbial cell membranes and acidifying the cell interior — the reason pickling in vinegar has preserved vegetables, fish and eggs for millennia. Food-grade acetic acid is typically diluted to familiar vinegar strengths, while glacial acetic acid is a corrosive industrial chemical handled with care.