acide malique'', which is derived from the
Latin
Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
word for apple, ''
mālum''—as is its
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
name ''
Malus
''Malus'' ( or ) is a genus of about 30–55 species of small deciduous trees or shrubs in the family Rosaceae, including the domesticated orchard apple, crab apples, wild apples, and rainberries.
The genus is native to the temperate zone ...
''.
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)''.
Malic acid is the main acid in many fruits, including
apricot
An apricot (, ) is a fruit, or the tree that bears the fruit, of several species in the genus '' Prunus''.
Usually, an apricot is from the species '' P. armeniaca'', but the fruits of the other species in ''Prunus'' sect. ''Armeniaca'' are al ...
s,
blackberries
The blackberry is an edible fruit produced by many species in the genus ''Rubus'' in the family (biology), family Rosaceae, hybrids among these species within the subgenus ''Rubus'', and hybrids between the subgenera ''Rubus'' and ''Idaeobatus' ...
,
blueberries
Blueberries are a widely distributed and widespread group of perennial flowering plants with blue or purple berries. They are classified in the section ''Cyanococcus'' within the genus ''Vaccinium''. ''Vaccinium'' also includes cranberries, bi ...
,
cherries
A cherry is the fruit of many plants of the genus '' Prunus'', and is a fleshy drupe (stone fruit).
Commercial cherries are obtained from cultivars of several species, such as the sweet ''Prunus avium'' and the sour ''Prunus cerasus''. The ...
,
grape
A grape is a fruit, botanically a berry, of the deciduous woody vines of the flowering plant genus '' Vitis''. Grapes are a non- climacteric type of fruit, generally occurring in clusters.
The cultivation of grapes began perhaps 8,000 years a ...
s,
mirabelles,
peach
The peach (''Prunus persica'') is a deciduous tree first domesticated and cultivated in Zhejiang province of Eastern China. It bears edible juicy fruits with various characteristics, most called peaches and others (the glossy-skinned, n ...
es,
pear
Pears are fruits produced and consumed around the world, growing on a tree and harvested in the Northern Hemisphere in late summer into October. The pear tree and shrub are a species of genus ''Pyrus'' , in the Family (biology), family Rosacea ...
s,
plum
A plum is a fruit of some species in ''Prunus'' subg. ''Prunus'.'' Dried plums are called prunes.
History
Plums may have been one of the first fruits domesticated by humans. Three of the most abundantly cultivated species are not found ...
s, and
quince
The quince (; ''Cydonia oblonga'') is the sole member of the genus ''Cydonia'' in the Malinae subtribe (which also contains apples and pears, among other fruits) of the Rosaceae family. It is a deciduous tree that bears hard, aromatic bright ...
and is present in lower concentrations in other fruits, such as
citrus. It contributes to the sourness of unripe apples.
Sour apple
The Granny Smith, also known as a green apple or sour apple, is an apple cultivar which originated in Australia in 1868. It is named after Maria Ann Smith, who propagated the cultivar from a chance seedling. The tree is thought to be a hybri ...
s contain high proportions of the acid. It is present in
grape
A grape is a fruit, botanically a berry, of the deciduous woody vines of the flowering plant genus '' Vitis''. Grapes are a non- climacteric type of fruit, generally occurring in clusters.
The cultivation of grapes began perhaps 8,000 years a ...
s and in most wines with concentrations sometimes as high as 5 g/L. It confers a tart taste to
wine
Wine is an alcoholic drink typically made from Fermentation in winemaking, fermented grapes. Yeast in winemaking, Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different ...
; the amount decreases with increasing fruit
ripeness
In United States law, ripeness refers to the readiness of a case for litigation; "a claim is not ripe for adjudication if it rests upon contingent future events that may not occur as anticipated, or indeed may not occur at all." For example, if a ...
. The taste of malic acid is very clear and pure in
rhubarb
Rhubarb is the fleshy, edible stalks ( petioles) of species and hybrids (culinary rhubarb) of '' Rheum'' in the family Polygonaceae, which are cooked and used for food. The whole plant – a herbaceous perennial growing from short, thick rhi ...
, a plant for which it is the primary flavor. It is also the compound responsible for the tart flavor of
sumac
Sumac ( or ), also spelled sumach, is any of about 35 species of flowering plants in the genus ''Rhus'' and related genera in the cashew family (Anacardiaceae). Sumacs grow in subtropical and temperate regions throughout the world, including Eas ...
spice. It is also a component of some artificial
vinegar
Vinegar is an aqueous solution of acetic acid and trace compounds that may include flavorings. Vinegar typically contains 5–8% acetic acid by volume. Usually, the acetic acid is produced by a double fermentation, converting simple sugars to eth ...
flavors, such as "salt and vinegar" flavored potato chips.
In citrus, fruits produced in organic farming contain higher levels of malic acid than fruits produced in conventional agriculture.
The process of
malolactic fermentation
Malolactic conversion (also known as malolactic fermentation or MLF) is a process in winemaking in which tart-tasting malic acid, naturally present in grape must, is converted to softer-tasting lactic acid. Malolactic fermentation is most often ...
converts malic acid to much milder
lactic acid
Lactic acid is an organic acid. It has a molecular formula . It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as well as nat ...
. Malic acid occurs naturally in all fruits and many vegetables, and is generated in fruit metabolism.
Malic acid, when added to food products, is denoted by
E number
E numbers ("E" stands for "Europe") are codes for substances used as food additives, including those found naturally in many foods such as vitamin C, for use within the European Union (EU) and European Free Trade Association (EFTA). Commonly ...
E296. It is sometimes used with or in place of the less sour
citric acid
Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in ...
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
food additive
Food additives are substances added to food to preserve Taste, flavor or enhance taste, appearance, or other sensory qualities. Some additives have been used for centuries as part of an effort to preserve food, for example vinegar (pickling), sal ...
in the EU, US
and Australia and New Zealand (where it is listed by its
INS number
The International Numbering System for Food Additives (INS) is a European-based naming system for food additives, aimed at providing a short designation of what may be a lengthy actual name."Class Names and the International Numbering System for Fo ...
296).
Malic acid contains 10 kJ (2.39 kilocalories) of energy per gram.
Production and main reactions
Racemic
In chemistry, a racemic mixture, or racemate (), is one that has equal amounts of left- and right-handed enantiomers of a chiral molecule or salt. Racemic mixtures are rare in nature, but many compounds are produced industrially as racemates. ...
malic acid is produced industrially by the double hydration of
maleic anhydride
Maleic anhydride is an organic compound with the formula C2H2(CO)2O. It is the acid anhydride of maleic acid. It is a colorless or white solid with an acrid odor. It is produced industrially on a large scale for applications in coatings and pol ...
. In 2000, American production capacity was 5,000 tons per year. The
enantiomer
In chemistry, an enantiomer ( /ɪˈnænti.əmər, ɛ-, -oʊ-/ ''ih-NAN-tee-ə-mər''; from Ancient Greek ἐνάντιος ''(enántios)'' 'opposite', and μέρος ''(méros)'' 'part') – also called optical isomer, antipode, or optical anti ...
s may be separated by
chiral resolution
Chiral resolution, or enantiomeric resolution, is a process in stereochemistry for the separation of racemic compounds into their enantiomers. It is an important tool in the production of optically active compounds, including drugs. Another term wi ...
of the racemic mixture. ''S''-Malic acid is obtained by fermentation of
fumaric acid
Fumaric acid is an organic compound with the formula HO2CCH=CHCO2H. A white solid, fumaric acid occurs widely in nature. It has a fruit-like taste and has been used as a food additive. Its E number is E297.
The salts and esters are known as fu ...
.
Self-condensation Self-condensation is an organic reaction in which a chemical compound containing a carbonyl group acts both as the electrophile and the nucleophile in an aldol condensation. It is also called a symmetrical aldol condensation as opposed to a mixed ...
of malic acid in the presence of
fuming sulfuric acid gives the
pyrone coumalic acid:
:
Note that this scheme is incorrect. 4 H
2O and 2 CO (carbon monoxide, not carbon dioxide) are liberated during the condensation.
Malic acid was important in the discovery of the
Walden inversion
Walden inversion is the inversion of a stereogenic center in a chiral molecule in a chemical reaction. Since a molecule can form two enantiomers around a stereogenic center, the Walden inversion converts the configuration of the molecule fro ...
and the
Walden cycle, in which (−)-malic acid first is converted into (+)-chlorosuccinic acid by action of
phosphorus pentachloride
Phosphorus pentachloride is the chemical compound with the formula PCl5. It is one of the most important phosphorus chlorides, others being PCl3 and POCl3. PCl5 finds use as a chlorinating reagent. It is a colourless, water-sensitive and mois ...
. Wet
silver oxide
Silver oxide is the chemical compound with the formula Ag2O. It is a fine black or dark brown powder that is used to prepare other silver compounds.
Preparation
Silver oxide can be prepared by combining aqueous solutions of silver nitrate and a ...
then converts the chlorine compound to (+)-malic acid, which then reacts with PCl
5 to the (−)-chlorosuccinic acid. The cycle is completed when silver oxide takes this compound back to (−)-malic acid.
Uses
-malic acid is used to
resolve
Resolve may refer to:
* ''Resolve'' (Lagwagon album)
* ''Resolve'' (Last Tuesday album)
* "Resolve" (song), by the Foo Fighters
*''The Resolve'', a 1915 American silent short drama film
* "Resolve" (''One Tree Hill'' episode)
*''Resolve'', a Briti ...
α-phenylethylamine, a versatile resolving agent in its own right.
Plant defense
Soil supplementation with
molasses
Molasses () is a viscous substance resulting from refining sugarcane or sugar beets into sugar. Molasses varies in the amount of sugar, method of extraction and age of the plant. Sugarcane molasses is primarily used to sweeten and flavour foods ...
increases microbial synthesis of MA. This is thought to occur naturally as part of
soil microbe suppression of disease, so
soil amendment
A soil conditioner is a product which is added to soil to improve the soil’s physical qualities, usually its fertility (ability to provide nutrition for plants) and sometimes its mechanics. In general usage, the term "soil conditioner" is often ...
with molasses can be used as a
crop
A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydropon ...
treatment in horticulture.
Interactive pathway map
See also
*
Acids in wine
The acids in wine are an important component in both winemaking and the finished product of wine. They are present in both grapes and wine, having direct influences on the color, balance and taste of the wine as well as the growth and vitality of ...
*
Citrate malate shuttle
*
Crassulacean acid metabolism
Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions that allows a plant to photosynthesize during the day, but only exchange gases at night. ...
*
Malate-aspartate shuttle
*
Maleic acid
Maleic acid or ''cis''-butenedioic acid is an organic compound that is a dicarboxylic acid, a molecule with two carboxyl groups. Its chemical formula is HO2CCH=CHCO2H. Maleic acid is the ''cis''-isomer of butenedioic acid, whereas fumaric ac ...
, resulting from malic acid dehydration
References
External links
Malic acid MS SpectrumCalculator: Water and solute activities in aqueous malic acid
{{DEFAULTSORT:Malic Acid
Cellular respiration
Citric acid cycle compounds
Cosmetics chemicals
Dicarboxylic acids
Food acidity regulators
Alpha hydroxy acids
Acids in wine
Chelating agents
E-number additives