It is a dicarboxylic acid that is made by all living organisms, contributes to the sour taste of fruits, and is used as a food additive.

Malic acid has two stereoisomeric forms (L- and D-enantiomers), though only the L-isomer exists naturally.

The related Latin word mālus, meaning 'apple tree', is used as the name of the genus Malus, which includes all apples and crabapples;[5] and is the origin of other taxonomic classifications such as Maloideae, Malinae, and Maleae.

In the citric acid cycle, (S)-malate is an intermediate, formed by the addition of an -OH group on the si face of fumarate.

Malic acid was first isolated from apple juice by Carl Wilhelm Scheele in 1785.

[7][8] In German it is named Äpfelsäure (or Apfelsäure) after plural or singular of a sour thing from the apple fruit, but the salt(s) are called Malat(e).

[10] It confers a tart taste to wine; the amount decreases with increasing fruit ripeness.

The taste of malic acid is very clear and pure in rhubarb, a plant for which it is the primary flavor.

[16] Racemic malic acid is produced industrially by the double hydration of maleic anhydride.