Stability of Iodine in Salt Fortified with Iodine and Iron

Abstract

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.

Keywords

Double-fortified salt iodine-deficiency disorders iodized salt iodine stability iron-deficiency anemia modified orthophosphoric acid method

References

World Bank. Enriching lives: Overcoming vitamin and mineral malnutrition in developing countries. Washington, DC: World Bank, Report no. 13800, November 1994.

Adamson

. Vitamin and mineral deficiency: A global progress report. Oxfordshire, UK: UNICEF/Micronutrient Initiative, 2004.

Ranganathan

Sundaresan

Raghavendra

Kalyani

. Dry mixing technique for the large scale production of iodine fortified salt in India. Asia Pacific J Clin Nutr 1997;6:92–4.

Ranganathan

Rao

BSN

Reddy

Prakash

Sundaresan

Ansari

. A new process for stabilizing iodine in iodized salt. In: Geertman

, ed. Salt 2000. 8th World Salt Symposium. Vol 2. The Hague: Elsevier, 2000:1051–6.

Ranganathan

. Fortification of salt with iron: Use of polyphosphate stabilizers. Food Chem 1992; 45: 263–7.

Ranganathan

Dillikumar

Ramamoorthy

Reddy

. Large-scale production of iron fortified salt. J Food Sci Technol 1993;30:166–8.

Narasinga Rao

. Fortification of salt with iron and iodine to control anaemia and goiter: Development of a new formula with good stability and bioavailability of iron and iodine. Food Nutr Bull 1994;15:32–9.

JECFA (Joint FAO/WHO Expert Committee on Food Additives). Compendium of food additive specifications. Vol. 2. Combined specifications from the first to the thirty-seventh meeting (1956–1990). FAO Food and Nutrition Paper 52/2. Rome: Food and Agriculture Organization, 1992.

Ranganathan

Reddy

Ramamoorthy

. Large-scale production of salt fortified with iodine and iron. Food Nutr Bull 1996;17:73–8.

10.

Ranganathan

Singotamu

. Scanning electron microscope studies on iodine. Scanning 1998;20:271–3.

11.

Nair

Sesikaran

Ranganathan

Sivakumar

. Bio-effect and safety of long term feeding of common salt fortified with iron and iodine (double-fortified salt) in rat. Nutr Res 1998;18:121–9.

12.

Nair

Brahmam

GNV

Ranganathan

Vijayaraghavan

Sivakumar

Krishnaswamy

. Impact evaluation of iron and iodine fortified salt. Indian J Med Res 1998;108:203–11.

13.

Brahmam

GNV

Nair

Laxmaiah

Gal Reddy

Ranganathan

Vishnuvardhana Rao

Naidu

Vijayaraghavan

Sivakumar

Krishanaswamy

Sastry

Ram

Rao

Reddy

. Community trials with iron and iodine fortified salt (double-fortified salt). In: Geertman

, ed. Salt 2000. 8th World Salt Symposium. Vol. 2. The Hague: Elsevier, 2000:955–60.

14.

Sivakumar

Brahmam

GNV

Madhavan Nair

Ranganathan

Vishnuvardhan Rao

Vijayaraghvan

Krishnaswamy

. Prospects of fortification of salt with iron and iodine. Br J Nutr 2001;85(suppl 2):S167–73.

15.

Sivakumar

Nair

. Double fortified salt at crossroads. Indian J Pediatr 2002;69:617–23.

16.

Titration methods for salt iodine analysis. In: Sullivan

Houston

Gorstein

Cervinskas

, eds. Monitoring universal salt iodization programmes. Atlanta, GA, USA: Programme against Micronutrient Malnutrition/Micronutrient Initiative/International Council for Control of Iodine Deficiency Disorders, 1995:86–9.

17.

Operational evaluation of the stability of iodine in double-fortified salt: A multicentric study. Interim report, Hyderabad, India: National Institute of Nutrition (Indian Council of Medical Research), January 2003.

18.

Ranganathan

Karmarkar

. Estimation of iodine in salt fortified with iodine and iron. Indian J Med Res 2006;123:531–40.

19.

Kolthoff

Belcher

. Volumetric analysis. Vol III. Titration methods: Oxidation-reduction reactions. New York: Interscience Publishers, Inc., 1957:247.

20.

Kolthoff

Belcher

. Volumetric analysis. Vol III. Titration methods: Oxidation-reduction reactions. New York: Interscience Publishers, Inc., 1957:235.

21.

Wong

. Hawk's physiological chemistry, 14th ed. New York: McGraw-Hill, 1965:1094.

22.

Ranganathan

Narasinga Rao

. Stability of iodine in iodized salt. Indian Food Ind 1986;5:122–4.

23.

Chauan

Bhatt

Majeethia

. Stability of iodized salt with respect to iodine content. Res Ind 1982;37:38–41.

24.

Pandav

Anand

Karmarkar

. Costing of a salt iodine monitoring laboratory in India. Natl Med J India 1994;7:13.

25.

Kelly

. Studies on the stability of iodine compounds in iodized salt. Bull World Health Organ 1953;9:217–30.

26.

Holman

McCartney

. Iodized salt. In: WHO Monograph Series No. 44. Endemic goitre. Geneva: World Health Organization, 1960:424–6.