Iodine Compounds
The most commonly used compounds in the iodization of foods are the iodides and iodates of sodium and potassium.
These are the additives allowed by Codex Alimentarius in the iodization of salt.
The iodide compounds are cheaper, more soluble and have a higher iodine content (so that les is needed to achieve the same level of iodization) than the corresponding iodates.
Iodates are more stable under conditions of high moisture, high ambient temperature sunlight, aeration and the present of impurities.
The use of iodates is therefore recommend for use in developing countries.
Potassium iodide is well suited in cases where the salt is dry, free from impurities and has a slightly alkaline pH.
Otherwise the iodine may be oxidized to molecular iodine and lost through evaporation.
If excess water is present the iodide may separated from salt in the water film.
Loss of iodide can be reduced through the addition of stabilizers such as 0.1% sodium thiosulphate and 0.1% calcium hydroxide combined or 0.04% dextrose and 0.006% sodium bicarbonate.
Calcium salts have been used with some report of off flavor due to the calcium ions.
The calcium compound is also much less water soluble than the sodium and potassium compounds and this further limits of applicability.
Iodine Compounds
