Increase of iodine content in brine-salted soft, semi-hard and hard cheeses by diffusion of iodide

Iodised salt (supplemented with potassium iodide) is the primary source of iodine in Switzerland, but it is rarely used in the manufacture of cheese. In the present study, the diffusion of iodide and chloride in experimentally produced soft, semi-hard and hard cheeses was investigated after brine-salting and subsequent ripening with iodised or non-iodised salt. Diffusion of iodide (I^-) and chloride (Cl^-) into the cheeses was monitored by zonal analyses at different times of ripening. The concurrent diffusion of the two ions in the aqueous phase of cheeses was modelled using Fick's law and the apparent diffusion coefficients (D_app) were determined. The results showed that iodide diffuses more slowly into the interior of the cheeses than chloride. Although the ripened cheeses still showed a concentration gradient between rind and centre, an average increase of 402 ± 30 µg kg^-1 iodine was achieved in the edible part of the cheeses treated with iodised salt. Based on a national food survey, the hypothetical contribution of cheese to the dietary iodine intake was estimated. If cheese was produced with iodised salt, it would cover approximately 10% of the recommended daily iodine intake (150 µg d^-1). Therefore, the use of iodised salt in cheese production would make an important contribution to a iodine supply for population groupswith borderline iodine deficiency.