Other names for the additive (synonyms)
General Information
The food additive E333(ii) is a subtype of the additive E333 (calcium citrates) and is known as calcium di-citrate.
It is a doubly-substituted acidic salt of citric (lemon) acid, in which two of the three hydrogen atoms in the molecule are replaced by calcium ions.
The chemical formula of calcium di-citrate is (C6H7O7)2Ca2·3H2O.
The production of calcium di-citrate is based on the partial neutralization of citric acid with a calcium source (most often calcium carbonate or calcium hydroxide) in an aqueous medium. Unlike complete precipitation, this method requires strict adherence to a 1:1 stoichiometric ratio of reagents. Controlling the pH and reaction temperature is critically important, as deviations can result in the formation of a mixture of different calcium citrates.
Compared to calcium mono-citrate (E333(i)), calcium di-citrate has lower solubility and a more neutral character in aqueous solutions. Compared to calcium tri-citrate (E333(iii)), it contains a smaller amount of calcium but is more stable in liquid and semi-liquid systems and less prone to precipitation.
Due to the intermediate degree of hydrogen substitution by calcium, E333(ii) combines the properties of an acidity regulator and a mineral supplement, providing gentle acidity adjustment without significantly affecting the product's taste.
In the food industry, E333(ii) is used as an acidity regulator and a source of calcium in products where a combination of stability and a neutral taste profile is important.
Calcium di-citrate is used in dairy products, especially in yogurts, fermented milk drinks, and desserts. The additive E333(ii) is also applied in fruit fillings, sauces, and puree-like products, where it is necessary to avoid excessive acidity, characteristic of calcium mono-citrate (E333(i)), while preventing precipitation typical for calcium tri-citrate (E333(iii)).
In the confectionery industry, the acidity regulator E333(ii) is used in fillings, jelly products, and creams for even distribution of calcium and flavor stabilization without significantly affecting the organoleptic properties of the finished product.
For more details on the properties of calcium citrates, their effects on the human body, and links to scientific studies, see the material on the food additive E333.