Fortification of salt

Salt has been favoured as a carrier for iodine due to its wide spread coverage, effectiveness, simple technology involved and low cost.

Based on the suitability of salt as a widely used and low cost vehicle, fortification of salt with other nutrients, mainly iron, is ongoing.

Selecting a suitable fortificant for salt iodisation

According to the Codex standard for food grade salt, potassium or sodium iodides and iodates can be used(FAO/WHO, 1995).

The iodates are more stable under a wide range of conditions. Potassium iodate form is recommended.

Iron fortificant for salt must not discolour the salt nor impart a flavour or odour and remains stable and bio-available on storage. Ferrous fumarate, ferric orthophosphate, ferrous pyrophosphate, and more recently (2004) micronized ferric pyrophosphate have been used. The iron compound must be chelated or encapsulated.

Adding the fortificant to the salt

There are four major technologies used in the addition of iodine to salt:

• Dry mixing
• Drip feed addition
• Spray mixing
• Submersion
• For iron fortification: dry mixing by ribbon blender or a screw type conveyor mixer with a suitable feeder can be used

Fortification losses during:

• Boiling of the salt solutions lead to negligible iodine loss.
• Storage i.e. leaving bags of salt open in warm, humid environments does lead to losses of the added iodine.
• Storing iodised salt in direct sunlight has an effect on iodine content.

Stability studies of iodised salt using potassium iodate as the fortificant demonstrated that there was no significant loss of iodine on storage in polyethylene bags for up to two years