Malic acid

Malic acid is a organic compound that is found in many fruits and vegetables, most notably apples. It is a dicarboxylic acid that is made by all living organisms, contributes to the pleasantly sour taste of fruits, and is used in food preparation and beverages for its sour taste.

Chemistry[edit | edit source]

Malic acid has two stereoisomeric forms (L- and D-enantiomers), though only the L-isomer exists naturally. The salts and esters of malic acid are known as malates. The malate anion is an intermediate in the citric acid cycle.

Biosynthesis[edit | edit source]

L-Malic acid is the naturally occurring form, whereas a mixture of L- and D-malic acid is produced synthetically. L-Malic acid is synthesized in the cytosol of plant cells by the enzyme malate dehydrogenase, a part of the oxidative decarboxylation process.

Uses[edit | edit source]

Malic acid contributes to the sourness of green apples. It is present in grapes and in most wines with concentrations sometimes as high as 5 g/l. It confers a tart taste to wine, although the amount decreases with increasing fruit ripeness. The process of malolactic fermentation converts malic acid to much milder lactic acid.

Safety[edit | edit source]

Malic acid, when added to food products, is denoted by E number E296. Malic acid is the source of extreme tartness in United States confectionery, the so-called extreme candy. It is also used with or in place of the less sour citric acid in sour sweets. These sweets are sometimes labeled with a warning that excessive consumption can cause irritation of the mouth. It is approved for use in the EU, US and Australia and New Zealand.

See also[edit | edit source]

Malic acid Resources
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