Calcium diglutamate
Calcium diglutamate, sometimes abbreviated CDG and also called calcium biglutamate, is a compound with formula Ca2. It is a calcium acid salt of glutamic acid. CDG is a flavor enhancer —it is the calcium analog of monosodium glutamate. 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.
Synthesis and reactions
Calcium di-glutamate can be prepared by reacting calcium carbonate with two molar equivalents of glutamic acid: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 and both carboxylic-acid groups 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 di-L-glutamate can be prepared through metathesis with manganese(II) sulphate: