Malic acid

Last updated
Malic acid
Apfelsaure3.svg
Malic-acid-3D-balls.png
Sample of racemic malic acid.jpg
DL-Malic acid
Names
Preferred IUPAC name
2-Hydroxybutanedioic acid
Other names
  • Hydroxybutanedioic acid
  • 2-Hydroxysuccinic acid
  • (L/D)-Malic acid
  • (±)-Malic acid
  • (S/R)-Hydroxybutanedioic acid
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.027.293 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 230-022-8
E number E296 (preservatives)
KEGG
PubChem CID
UNII
  • InChI=1S/C4H6O5/c5-2(4(8)9)1-3(6)7/h2,5H,1H2,(H,6,7)(H,8,9) Yes check.svgY
    Key: BJEPYKJPYRNKOW-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C4H6O5/c5-2(4(8)9)1-3(6)7/h2,5H,1H2,(H,6,7)(H,8,9)
    Key: BJEPYKJPYRNKOW-UHFFFAOYAM
  • O=C(O)CC(O)C(=O)O
Properties
C4H6O5
Molar mass 134.09 g/mol
AppearanceColorless
Density 1.609 g⋅cm−3
Melting point 130 °C (266 °F; 403 K)
558 g/L (at 20 °C) [1]
Acidity (pKa)pKa1 = 3.40
pKa2 = 5.20 [2]
pKa3 = 14.5 [3]
Hazards
GHS labelling:
GHS-pictogram-exclam.svg
Flash point 203 °C [4]
Related compounds
Other anions
Malate
Succinic acid
Tartaric acid
Fumaric acid
Related compounds
Butanol
Butyraldehyde
Crotonaldehyde
Sodium malate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Malic acid is an organic compound with the molecular formula HO2CCH(OH)CH2CO2H. 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 salts and esters of malic acid are known as malates. The malate anion is a metabolic intermediate in the citric acid cycle.

Contents

Etymology

The word 'malic' is derived from Latin mālum, meaning 'apple'. 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 the origin of other taxonomic classifications such as Maloideae, Malinae, and Maleae.

Biochemistry

L-Malic acid is the naturally occurring form, whereas a mixture of L- and D-malic acid is produced synthetically.

Malate plays an important role in biochemistry. In the C4 carbon fixation process, malate is a source of CO2 in the Calvin cycle. In the citric acid cycle, (S)-malate is an intermediate, formed by the addition of an -OH group on the si face of fumarate. It can also be formed from pyruvate via anaplerotic reactions.

Malate is also synthesized by the carboxylation of phosphoenolpyruvate in the guard cells of plant leaves. Malate, as a double anion, often accompanies potassium cations during the uptake of solutes into the guard cells in order to maintain electrical balance in the cell. The accumulation of these solutes within the guard cell decreases the solute potential, allowing water to enter the cell and promote aperture of the stomata.

In food

Malic acid was first isolated from apple juice by Carl Wilhelm Scheele in 1785. [6] Antoine Lavoisier in 1787 proposed the name acide malique , which is derived from the Latin word for apple, mālum as is its genus name Malus . [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). Malic acid is the main acid in many fruits, including apricots, blackberries, blueberries, cherries, grapes, mirabelles, peaches, pears, plums, and quince [9] and is present in lower concentrations in other fruits, such as citrus. It contributes to the sourness of unripe apples. Sour apples contain high proportions of the acid. It is present in grapes and in most wines with concentrations sometimes as high as 5 g/L. [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. It is also the compound responsible for the tart flavor of sumac spice. It is also a component of some artificial vinegar flavors, such as "salt and vinegar" flavored potato chips. [11]

The process of malolactic fermentation converts malic acid to much milder lactic acid. Malic acid occurs naturally in all fruits and many vegetables, and is generated in fruit metabolism. [12]

Malic acid, when added to food products, is denoted by E number E296. It is sometimes used with or in place of the less sour citric acid 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 in the EU, [13] US [14] and Australia and New Zealand [15] (where it is listed by its INS number 296).

Malic acid contains 10 kJ (2.39 kilocalories) of energy per gram. [16]

Production and main reactions

Racemic malic acid is produced industrially by the double hydration of maleic anhydride. In 2000, American production capacity was 5,000 tons per year. The enantiomers may be separated by chiral resolution of the racemic mixture. S-Malic acid is obtained by fermentation of fumaric acid. [17]

Self-condensation of malic acid in the presence of fuming sulfuric acid gives the pyrone coumalic acid: [18]

2 HO2CCH(OH)CH2CO2H → HO2CC4H3O2 + 2 CO + 4 H2O

Carbon monoxide and water are liberated during this reaction.

Malic acid was important 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 converts 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.

L-malic acid is used to resolve α-phenylethylamine, a versatile resolving agent in its own right. [19]

Plant defense

Soil supplementation with molasses increases microbial synthesis of MA. This is thought to occur naturally as part of soil microbe suppression of disease, so soil amendment with molasses can be used as a crop treatment in horticulture. [20]

Interactive pathway map

Click on genes, proteins and metabolites below to link to respective articles. [§ 1]

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WP534.png go to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to articlego to WikiPathwaysgo to articlego to Entrezgo to article
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Glycolysis and Gluconeogenesis edit
  1. The interactive pathway map can be edited at WikiPathways: "GlycolysisGluconeogenesis_WP534".

See also

Related Research Articles

<span class="mw-page-title-main">Benzoic acid</span> Organic compound (C6H5COOH)

Benzoic acid is a white solid organic compound with the formula C6H5COOH, whose structure consists of a benzene ring with a carboxyl substituent. The benzoyl group is often abbreviated "Bz", thus benzoic acid is also denoted as BzOH, since the benzoyl group has the formula –C6H5CO. It is the simplest aromatic carboxylic acid. The name is derived from gum benzoin, which was for a long time its only source.

<span class="mw-page-title-main">Vinegar</span> Liquid consisting mainly of acetic acid and water

Vinegar is an aqueous solution of acetic acid and trace compounds that may include flavorings. Vinegar typically contains from 5% to 8% acetic acid by volume. Usually, the acetic acid is produced by a double fermentation, converting simple sugars to ethanol using yeast, and ethanol to acetic acid using acetic acid bacteria. Many types of vinegar are made, depending on source materials. The product is now mainly used in the culinary arts as a flavorful, acidic cooking ingredient, or in pickling. Various types are used as condiments or garnishes, including balsamic vinegar and malt vinegar.

<span class="mw-page-title-main">Orange juice</span> Juice made from oranges

Orange juice is a liquid extract of the orange tree fruit, produced by squeezing or reaming oranges. It comes in several different varieties, including blood orange, navel oranges, valencia orange, clementine, and tangerine. As well as variations in oranges used, some varieties include differing amounts of juice vesicles, known as "pulp" in American English, and "(juicy) bits" in British English. These vesicles contain the juice of the orange and can be left in or removed during the manufacturing process. How juicy these vesicles are depend upon many factors, such as species, variety, and season. In American English, the beverage name is often abbreviated as "OJ".

In food processing, brining is treating food with brine or coarse salt which preserves and seasons the food while enhancing tenderness and flavor with additions such as herbs, spices, sugar, caramel or vinegar. Meat and fish are typically brined for less than twenty-four hours while vegetables, cheeses and fruit are brined in a much longer process known as pickling. Brining is similar to marination, except that a marinade usually includes a significant amount of acid, such as vinegar or citrus juice. Brining is also similar to curing, which usually involves significantly drying the food, and is done over a much longer time period.

<span class="mw-page-title-main">Citric acid</span> Weak organic 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 the metabolism of all aerobic organisms.

<span class="mw-page-title-main">Calamansi</span> Hybrid species of citrus

Calamansi, also known as calamondin, Philippine lime, or Philippine lemon, is an economically important citrus hybrid cultivated predominantly in the Philippines. It is native to the Philippines, parts of Indonesia, Malaysia, and Brunei, as well as parts of southern China and Taiwan.

<span class="mw-page-title-main">Tartaric acid</span> Organic acid found in many fruits

Tartaric acid is a white, crystalline organic acid that occurs naturally in many fruits, most notably in grapes, but also in tamarinds, bananas, avocados and citrus. Its salt, potassium bitartrate, commonly known as cream of tartar, develops naturally in the process of fermentation. It is commonly mixed with sodium bicarbonate and is sold as baking powder used as a leavening agent in food preparation. The acid itself is added to foods as an antioxidant E334 and to impart its distinctive sour taste. Naturally occurring tartaric acid is a useful raw material in organic chemical synthesis. Tartaric acid, an alpha-hydroxy-carboxylic acid, is diprotic and aldaric in acid characteristics, and is a dihydroxyl derivative of succinic acid.

<span class="mw-page-title-main">Pectin</span> Structural carbohydrate in the cell walls of land plants and some algae

Pectin is a heteropolysaccharide, a structural acid contained in the primary lamella, in the middle lamella, and in the cell walls of terrestrial plants. The principal chemical component of pectin is galacturonic acid which was isolated and described by Henri Braconnot in 1825. Commercially produced pectin is a white-to-light-brown powder, produced from citrus fruits for use as an edible gelling agent, especially in jams and jellies, dessert fillings, medications, and sweets; and as a food stabiliser in fruit juices and milk drinks, and as a source of dietary fiber.

<span class="mw-page-title-main">Lime (fruit)</span> Citrus fruit

A lime is a citrus fruit, which is typically round, green in color, 3–6 centimetres (1.2–2.4 in) in diameter, and contains acidic juice vesicles.

<i>Umeboshi</i> Sour, pickled Japanese fruit

Umeboshi are pickled (brined) ume fruits common in Japan. The word umeboshi is often translated into English as 'salted Japanese plums', 'Japanese plums' or 'preserved plums'. Ume is a species of fruit-bearing tree in the genus Prunus, which is often called a "plum", but is actually more closely related to the apricot. Pickled ume which are not dried are called umezuke (梅漬け).

<span class="mw-page-title-main">Malonic acid</span> Carboxylic acid with chemical formula CH2(COOH)2

Malonic acid (IUPAC systematic name: propanedioic acid) is a dicarboxylic acid with structure CH2(COOH)2. The ionized form of malonic acid, as well as its esters and salts, are known as malonates. For example, diethyl malonate is malonic acid's diethyl ester. The name originates from the Greek word μᾶλον (malon) meaning 'apple'.

<span class="mw-page-title-main">Fumaric acid</span> Organic compound

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 fumarates. Fumarate can also refer to the C
4
H
2
O2−
4
ion (in solution). Fumaric acid is the trans isomer of butenedioic acid, while maleic acid is the cis isomer.

<span class="mw-page-title-main">Food browning</span> Food process

Browning is the process of food turning brown due to the chemical reactions that take place within. The process of browning is one of the chemical reactions that take place in food chemistry and represents an interesting research topic regarding health, nutrition, and food technology. Though there are many different ways food chemically changes over time, browning in particular falls into two main categories: enzymatic versus non-enzymatic browning processes.

<span class="mw-page-title-main">Malolactic fermentation</span> Process in winemaking

Malolactic conversion 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 performed as a secondary fermentation shortly after the end of the primary fermentation, but can sometimes run concurrently with it. The process is standard for most red wine production and common for some white grape varieties such as Chardonnay, where it can impart a "buttery" flavor from diacetyl, a byproduct of the reaction.

<span class="mw-page-title-main">Soured milk</span> Milk-based food product

Soured milk denotes a range of food products produced by the acidification of milk. Acidification, which gives the milk a tart taste, is achieved either through bacterial fermentation or through the addition of an acid, such as lemon juice or vinegar. The acid causes milk to coagulate and thicken, inhibiting the growth of harmful bacteria and improving the product's shelf life. It is not good for making cheese.

<span class="mw-page-title-main">Preserved lemon</span> Type of pickle

Preserved lemon or lemon pickle is a condiment that is common in the cuisines of Indian subcontinent and Morocco. It was also found in 18th-century English cuisine.

<span class="mw-page-title-main">Acids in wine</span>

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 yeast during fermentation and protecting the wine from bacteria. The measure of the amount of acidity in wine is known as the “titratable acidity” or “total acidity”, which refers to the test that yields the total of all acids present, while strength of acidity is measured according to pH, with most wines having a pH between 2.9 and 3.9. Generally, the lower the pH, the higher the acidity in the wine. There is no direct connection between total acidity and pH. In wine tasting, the term “acidity” refers to the fresh, tart and sour attributes of the wine which are evaluated in relation to how well the acidity balances out the sweetness and bitter components of the wine such as tannins. Three primary acids are found in wine grapes: tartaric, malic, and citric acids. During the course of winemaking and in the finished wines, acetic, butyric, lactic, and succinic acids can play significant roles. Most of the acids involved with wine are fixed acids with the notable exception of acetic acid, mostly found in vinegar, which is volatile and can contribute to the wine fault known as volatile acidity. Sometimes, additional acids, such as ascorbic, sorbic and sulfurous acids, are used in winemaking.

<span class="mw-page-title-main">Lemon</span> Yellow citrus fruit

The lemon is a species of small evergreen tree in the flowering plant family Rutaceae, native to Asia, primarily Northeast India (Assam), Northern Myanmar, and China.

<span class="mw-page-title-main">Pickled fruit</span> Fruit that has been preserved by anaerobic fermentation in brine or immersion in vinegar

Pickled fruit refers to fruit that has been pickled. Pickling is the process of food preservation by either anaerobic fermentation in brine or immersion in vinegar. Many types of fruit are pickled. Some examples include peaches, apples, crabapples, pears, plums, grapes, currants, tomatoes and olives. Vinegar may also be prepared from fruit, such as apple cider vinegar.

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