What is Potassium Iodate?
Potassium iodate is a food ingredient that oxidizes and strengthens gluten protein bonds in bread dough almost immediately after mixing. It accelerates the reactions which allow the bread to rise during baking.
Properties of potassium iodate:1
- Chemical formula: KIO3
- Molecular weight: 214.02
- White, odorless, crystalline powder
- Water soluble
In the mid 1900s, bread making changed from the traditional method of bulk fermentation to new mechanical processes dependent on fast acting oxidizers.2 The less traditional processes (continuous, no time dough, chorleywood) use mechanical and chemical re-arrangement of the gluten structure to develop the dough.
The new processes allow for the use of larger amounts of fast acting oxidants or combinations of both slow and fast acting oxidants.
Similar to other oxidizing agents, this one enhances gluten formation and adjusts dough strength, elasticity and tolerance. It affects the sulfur-containing amino acids in the gluten proteins by helping the thiol (SH) groups form disulfide bridges between gluten molecules. The addition of this agent to flour allows for a stronger dough by creating a gluten matrix.
Outside of Europe and North America, potassium iodate (59.5% iodine) is the preferred source of iodine fortification for food and feed because of its stability.3 Potassium iodate is primarily added to salt as a source of iodine, but some countries (Russia, Tasmania) add it to bread.
This ingredient is often used in combination with the slow acting oxidizer potassium bromate. The use level for potassium iodate is small and often self limiting, since excessive amount produces bread with inferior qualities.
In the United States, potassium iodate is affirmed as a Generally Recognized as Safe (GRAS) food substance for use under the following conditions:
- Used in the manufacture of bread, not to exceed 0.0075 based on the weight of the flour.
- The ingredient is used as a dough strengthener
- Meets the specifications of the Food Chemical Codex (FCC) 3rd edition. (21 C.F.R. § 184.1635 2018)
In the European Union, Australia, New Zealand and Canada, the use of potassium iodate as a dough strengthener is banned.4
- FAO. Potassium Iodate Specification, “Compendium of Food Additive Specifications, Online Edition”. www.fao.org/fileadmin/user_upload/jecfa_additives/docs/Monograph1/Additive-340.pdf. Accessed 18 Jan. 2019.
- Zentner, H. “The oxidation of mechanically developed doughs.” J Sci Food Agric.15.9. 1964. pp 629-634.
- “Iron, vitamin A and iodine”, Guidelines on Food Fortification with Micronutrients. Edited by Lindsay Allen, Bruno de Benoist, Omar Dary and Richard Hurrell, WHO press, Switzerland, 2006.
- Cauvain, S, Young, L. Ingredient qualities and quantities in the Chorleywood Bread Process”, The Chorleywood Bread Process. WoodHead Publishing, England. 2006.