Calcium citrate Properties

Calcium citrate is an odorless white powder, practically insoluble in cold water. Calcium citrate is used as a chelating agent, buffer, organization coagulant, calcium fortified, emulsifying salts, etc.

Calcium citrate is the calcium salt of citric acid. It is commonly used as a food additive (E333), usually as a preservative, but sometimes for flavor. In this sense, it is similar to sodium citrate. Calcium citrate is also used as a water softener because the citrate ions can chelate unwanted metal ions. Calcium citrate is also found in some dietary calcium supplements (e.g. Citracal). Calcium makes up 24.1% of calcium citrate (anhydrous) and 21.1% of calcium citrate (tetrahydrate) by mass.

1. Production

Calcium citrate is an intermediate in the isolation of citric acid from the fermentation process by which citric acid is produced industrially. The citric acid in the broth solution is neutralized by calcium hydroxide, precipitating insoluble calcium citrate. This is then filtered off from the rest of the broth and washed to give clean calcium citrate.

The calcium citrate thus produced may be sold as-is, or it may be converted to citric acid using dilute sulfuric acid.

2. Properties

Name:Calcium citrate

EINECS:212-391-7

Molecular Formula:C12H10Ca3O14

CAS Registry Number:813-94-5 

Synonyms:Calciumcitrate (Ca3(O7C6H5)2) (7CI); Citric acid, calcium salt (2:3) (8CI); Acicontral; Citracal; Citrical; Tribasic calcium citrate; Tricalcium citrate; Tricalcium dicitrate; 1,2,3-Propanetricarboxylicacid, 2-hydroxy-, calcium salt (2:3);

InChI:InChI=1S/2C6H8O7.3Ca/c2*7-3(8)1-6(13,5(11)12)2-4(9)10;;;/h2*13H,1-2H2,(H,7,8)(H,9,10)(H,11,12);;;/q;;3*+2/p-6

Appearance:white powder or white to colourless crystals

Molecular Weight:498.4334

Density:1.63 g/cm3

Boiling Point:309.6 °C at 760 mmHg

Melting Point:120 °C (loses water)

Flash Point:155.2 °C

Solubility:0.1 M HCl: 0.01 M at 20 °C, clear, colorless

Stability:Stable. Incompatible with strong oxidizing agents.