Malic Acid

Malic acid is an <a href="http://en.wikipedia.org/wiki/Organic_compound" title="Organic compound" >organic compound</a> with the formula HO2CCH2CHOHCO2H. It is a <a href="http://en.wikipedia.org/wiki/Dicarboxylic_acid" title="Dicarboxylic acid" >dicarboxylic acid</a> which is made by all living organisms, contributes to the pleasantly 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 <a href="http://en.wikipedia.org/wiki/Salt_(chemistry)" title="Salt (chemistry)" >salts</a> and <a href="http://en.wikipedia.org/wiki/Ester" title="Ester" >esters</a> of malic acid are known asmalates. The malate anion is an intermediate in the <a href="http://en.wikipedia.org/wiki/Citric_acid_cycle" title="Citric acid cycle" >citric acid cycle</a>.

Malic acid was first isolated from <a href="http://en.wikipedia.org/wiki/Apple_juice" title="Apple juice" >apple juice</a> by <a href="http://en.wikipedia.org/wiki/Carl_Wilhelm_Scheele" title="Carl Wilhelm Scheele" >Carl Wilhelm Scheele</a> in 1785. <a href="http://en.wikipedia.org/wiki/Antoine_Lavoisier" title="Antoine Lavoisier" >Antoine Lavoisier</a> in 1787 proposed the name <a href="http://en.wiktionary.org/wiki/acide_malique" class="extiw" title="wikt:acide malique" >acide malique</a> which is derived from the <a href="http://en.wikipedia.org/wiki/Latin" title="Latin" >Latin</a> word for apple, <a href="http://en.wiktionary.org/wiki/malum#Etymology_2" class="extiw" title="wikt:malum" >mālum</a>.<a href="http://en.wikipedia.org/wiki/Malic_acid#cite_note-2" >[3]</a> Malic acid contributes to the sourness of green <a href="http://en.wikipedia.org/wiki/Apple" title="Apple" >apples</a>. It is present in <a href="http://en.wikipedia.org/wiki/Grape" title="Grape" >grapes</a> and in most wines with concentrations sometimes as high as 5 g/l.<a href="http://en.wikipedia.org/wiki/Malic_acid#cite_note-3" >[4]</a> It confers a tart taste to <a href="http://en.wikipedia.org/wiki/Wine" title="Wine" >wine</a>, although the amount decreases with increasing fruit <a href="http://en.wikipedia.org/wiki/Ripeness_(wine)" title="Ripeness (wine)" class="mw-redirect" >ripeness</a>. The process of<a href="http://en.wikipedia.org/wiki/Malolactic_fermentation" title="Malolactic fermentation" >malolactic fermentation</a> converts malic acid to much milder <a href="http://en.wikipedia.org/wiki/Lactic_acid" title="Lactic acid" >lactic acid</a>. Malic acid occurs naturally in all fruits and many vegetables, and is generated in fruit metabolism.<a href="http://en.wikipedia.org/wiki/Malic_acid#cite_note-4" >[5]</a>

Malic acid, when added to food products, is denoted by <a href="http://en.wikipedia.org/wiki/E_number" title="E number" >E number</a> E296. Malic acid is the source of extreme tartness in <a href="http://en.wikipedia.org/wiki/USA" title="USA" class="mw-redirect" >USA</a>-produced confectionery, the so-called extreme candy. It is also used with or in place of the less sour<a href="http://en.wikipedia.org/wiki/Citric_acid" title="Citric acid" >citric acid</a> in sour sweets. These sweets are sometimes labeled with a warning stating that excessive consumption can cause irritation of the mouth. It is approved for use as a <a href="http://en.wikipedia.org/wiki/Food_additive" title="Food additive" >food additive</a> in the EU,<a href="http://en.wikipedia.org/wiki/Malic_acid#cite_note-5" >[6]</a> USA<a href="http://en.wikipedia.org/wiki/Malic_acid#cite_note-6" >[7]</a> and Australia and New Zealand<a href="http://en.wikipedia.org/wiki/Malic_acid#cite_note-7" >[8]</a> (where it is listed by its INS number 296).