Calcium diglutamate, sometimes abbreviated CDG and also called calcium biglutamate, is a
compound with formula Ca(C
5H
8NO
4)
2. It is a
calcium
Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...
acid salt
An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen cation, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid.
The first category of acids are the ...
of
glutamic acid
Glutamic acid (symbol Glu or E; known as glutamate in its anionic form) is an α- amino acid that is used by almost all living beings in the biosynthesis of proteins. It is a non-essential nutrient for humans, meaning that the human body can ...
. CDG is a
flavor enhancer
A flavoring (or flavouring), also known as flavor (or flavour) or flavorant, is a food additive that is used to improve the taste or smell of food. It changes the perceptual impression of food as determined primarily by the chemoreceptors of t ...
(
E number
E numbers, short for Europe numbers, 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 ...
E623)—it is the calcium analog of
monosodium glutamate
Monosodium glutamate (MSG), also known as sodium glutamate, is a sodium salt of glutamic acid. MSG is found naturally in some foods including tomatoes and cheese in this glutamic acid form. MSG is used in cooking as a flavor enhancer with a ...
(MSG). Because the
glutamate is the actual flavor-enhancer, CDG has the same flavor-enhancing properties as MSG but without the increased sodium content. Notably, only the
L isomer is used in flavouring as
D-glutamate does not have an umami/savoury flavour.
As a soluble source of calcium ions, this chemical is also used as a
first-aid treatment for exposure to
hydrofluoric acid
Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colorless, acidic and highly corrosive. A common concentration is 49% (48–52%) but there are also stronger solutions (e.g. 70%) and pure HF has a boiling p ...
.
Synthesis and reactions
Calcium di-glutamate can be prepared by reacting
calcium carbonate
Calcium carbonate is a chemical compound with the chemical formula . It is a common substance found in Rock (geology), rocks as the minerals calcite and aragonite, most notably in chalk and limestone, eggshells, gastropod shells, shellfish skel ...
with two molar equivalents of
glutamic acid
Glutamic acid (symbol Glu or E; known as glutamate in its anionic form) is an α- amino acid that is used by almost all living beings in the biosynthesis of proteins. It is a non-essential nutrient for humans, meaning that the human body can ...
:
:CaCO
3 + 2 HOOC(CH
2)
2CH(NH
2)COOH → Ca(OOC(CH
2)
2CH(NH
3)COO)
2 + H
2O + CO
2↑
Concentration of the solution to a syrup under reduced pressure, followed by gradual crystallisation, affords the monohydrate.
Structurally, the glutamate anion is zwitterionic, with the amino group protonated (p''K''
a = 9.47) and both carboxylic-acid groups (p''K''
a = 2.10, 4.07) in their deprotonated carboxylate form.
Calcium di-
L-glutamate can be used to prepare other glutamates through metathesis with a soluble sulfate, carbonate or hydroxide salt. For example, manganese(II) di-
L-glutamate can be prepared through metathesis with
manganese(II) sulphate:
:Ca(OOC(CH
2)
2CH(NH
3)COO)
2 + MnSO
4 → Mn(OOC(CH
2)
2CH(NH
3)COO)
2 + CaSO
4↓
References
{{Calcium compounds
Glutamates
Calcium compounds
E-number additives