Stability of iodine in salt fortified with iodine and iron.
BACKGROUND
Determining the stability of iodine in fortified salt can be difficult under certain conditions. Current methods are sometimes unreliable in the presence of iron.


OBJECTIVE
To test the new method to more accurately estimate iodine content in double-fortified salt (DFS) fortified with iodine and iron by using orthophosphoric acid instead of sulfuric acid in the titration procedure.


METHODS
A double-blind, placebo-controlled study was carried out on DFS and iodized salt produced by the dry-mixing method. DFS and iodized salt were packed and sealed in color-coded, 0.5-kg, low-density polyethylene pouches, and 25 of these pouches were further packed and sealed in color-coded, double-lined, high-density polyethylene bags and transported by road in closed, light-protected containers to the International Council for the Control of Iodine Deficiency Disorders (ICCIDD), Delhi; the National Institute of Nutrition (NIN), Hyderabad; and the Orissa Unit of the National Nutrition Monitoring Bureau (NNMB), Bhubaneswar. The iodine content of DFS and iodized salt stored under normal room conditions in these places was measured by the modified method every month on the same prescribed dates during the first 6 months and also after 15 months. The iodine content of DFS and iodized salt stored under simulated household conditions was also measured in the first 3 months.


RESULTS
After the color code was broken at the end of the study, it was found that the DFS and iodized salt stored at Bhubaneswar, Delhi, and Hyderabad retained more or less the same initial iodine content (30-40 ppm) during the first 6 months, and the stability was not affected after 15 months. The proportion of salt samples having more than 30 ppm iodine was 100% in DFS and iodized salt throughout the study period. Daily opening and closing of salt pouches under simulated household conditions did not result in any iodine loss.


CONCLUSIONS
The DFS and iodized salt prepared by the dry-mixing method and stored at normal room conditions had excellent iodine stability for more than 1 year.
Ranganathan
Srinivasaiyengar
S
Isotope Division, National Institute of Nutrition, Indian Council of Medical Research, Hyderabad 500 007, India. drrangan@rediffmail.com
Karmarkar
Madhu G
MG
Krupadanam
Muddepaka
M
Brahmam
Ginnela N V
GN
Rao
Mendhu Vishnuvardhana
MV
Vijayaraghavan
Kamasamudram
K
Sivakumar
Bhattriprolu
B
D001682:Biological Availability; D004311:Double-Blind Method; D005504:Food Analysis / Q000379:methods*; D005511:Food Handling / Q000379:methods*; D005527:Food, Fortified; D006801:Humans; D007194:India; D007455:Iodine / Q000032:analysis* / Q000493:pharmacokinetics; D019266:Iron, Dietary / Q000032:analysis* / Q000493:pharmacokinetics; D010756:Phosphoric Acids / Q000737:chemistry; D011786:Quality Control; D017673:Sodium Chloride, Dietary; D013464:Sulfuric Acids / Q000737:chemistry; D013997:Time Factors; D016896:Treatment Outcome
D019266:Iron, Dietary; D010756:Phosphoric Acids; D017673:Sodium Chloride, Dietary; D013464:Sulfuric Acids; C034024:iodized salt; D007455:Iodine; C033158:sulfuric acid