Malic acid

Malic acid is a tart-tasting organic acid that plays a role in many sour or tart foods. The chemical structure of malic acid is HO₂C-CH₂-CH(OH)-CO₂H.

Apples contain malic acid, which contributes to the sourness of a green apple.

Malic acid can make a wine taste tart, although the amount decreases with increasing fruit ripeness. The process of malolactic fermentation converts malic acid to much milder lactic acid.