Acetic Acid
The short version
The acid in vinegar — used as a flavoring and preservative in pickled and acidified foods.
It's widely considered safe at the amounts used in food, so we mark it green. The Safety section below has the details.
Where it comes from
Produced naturally by acetic acid bacteria oxidizing ethanol. Used by humans since prehistory as vinegar. Industrially produced today by methanol carbonylation.
How it's used
Active ingredient of all vinegars. Used in pickles, salad dressings, mayonnaise, ketchup, and sauces. Provides flavor and microbial inhibition at low pH.
Safety profile
Generally regarded as safe at food concentrations. Concentrated acetic acid (above 25%) is corrosive and dangerous to handle.
Physical & chemical properties
Colorless liquid with pungent odor. Miscible with water. Weak acid (pKa 4.76). Effective antimicrobial in protonated form at low pH.
Regulation worldwide
Permitted globally without quantitative restriction for most food uses.
Educational information only. Not medical or dietary advice.