| Malic Acid |
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| dicarboxylic acids | |
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Malic acid is a Tart -tasting Organic di Carboxylic Acid that plays a role in many Sour or tart foods. In its ionised form it is Malate , an intermediate of the TCA Cycle along with Fumarate . It can also be formed from Pyruvate as one of the Anaplerotic Reactions . Apple s 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 . Malic acid, when added to food products, is denoted by E Number E296. In biological sources malic acid is Homochiral and only exists as the (-)-malic acid Enantiomer . Malic acid stars in the discovery of the Walden Inversion and the Walden cycle in which (-)-malic acid first is converted into (+)-chlorosuccinic acid by action of Phosphorus Pentachloride . Wet Silver Oxide then takes the chlorine compound to (+)-malic acid which then reacts with PCl5 to the (-)-chlorosuccinic acid. The cycle is completed when silver oxide takes this compound back to (-)-malic acid. Malic acid is the source of extreme tartness in so called "extreme candy", for example Mega Warheads . It is also used with or in place of the less sour Citric Acid in sour candies such as Jolly Rancher s and SweeTarts . These candies are sometimes labeled with a warning that excessive consumption can cause irritation of the mouth. SELF CONDENSATION Self-condensation of malic acid with Fuming Sulfuric Acid gives the Pyrone coumalic acid ''Coumaric acid'' Organic Syntheses , Coll. Vol. 4, p.201 (1963); Vol. 31, p.23 (1951) Online article : : HISTORY Malic acid was first isolated from Apple Juice by Carl Wilhelm Scheele in 1785. Antoine Lavoisier in 1787 proposed the name ''acide malique'' which is derived from the Latin word for apple, ''malum'' ''The Origin of the Names Malic, Maleic, and Malonic Acid'' Jensen, William B. J. Chem. Educ. 2007, 84, 924. Abstract . SEE ALSO Two other dicarboxylic acids have similar names and should not be confused with malic acid: REFERENCES EXTERNAL LINKS |
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