First a bit about bread. Bread can be made of many types of flour. What makes bread fluffy and chewy is gluten. Gluten is a long protein found in several grains, most specifically in wheat. Gluten is made of two different proteins called glutenin and gliadin. When wheat flour is milled it is called “green four”. The glutenin and gliadin proteins in the flour undergo a chemical change when exposed to oxygen making them stronger. When those stronger proteins combine with water they form gluten. (Dirndorf, 2017) Green flour is freshly milled flour with no oxidation and will yield a loaf unable to rise as the dough will not have enough stretch to capture the CO2 from the yeast. Aged flour has gone through long enough oxidation to form strong gluten bonds which yield elastic dough. Flour oxidation is a natural process and takes several days to achieve optimum gluten producing flour.

One can chemically age flour using potassium bromate. Potassium bromate (E924) is a halo containing compound that rapidly oxidizes glutenin and gliadin. Potassium bromate is made by adding electricity to a potassium bromide solution. By virtue of the high ionization energy and relatively low atomic radius of bromine, potassium bromate is highly reactive.  The high oxidation potential of bromate is reduced, or used, when potassium bromate is introduced to other compounds and to heat. (Perez, 2010) Unless the bromate is reduced completely in the baking process, it will continue to oxidize what it comes in contact with, in this case the human body. Oxidation in the human body is the precursor for cancer.

Bromate also effects the endocrine system, specifically the thyroid. Bromide is only one step removed from iodide, being smaller and having more electron affinity than iodide. Iodide as turned into iodine by the thyroid, is an essential player in the human endocrine system. When bromate is ingested it easily takes the place of iodine, reducing the amount of iodide for use in the thyroid. (Starek et al., 2016)

One can reduce exposure to potassium bromate by purchasing breads made with naturally aged rather than bromated flour. A safer aging agent in bread is ascorbic acid, which functions similarly chemically in bread but has many fewer effects on the human body. It’s not the gluten in the bread making your body crazy, it’s the potassium bromate.

Dirndorfer, Manfred (2017). Flour Quality: Flour Aging – The effects on flour quality and baking performance. Retreived from: on September 30, 2017

Perez, R. D., & Leon, A. E. (2010). Bromate Determination by X-Ray Fluorescence (XRF) to Identify Pre-Baking Potassium Bromate Addition in Bread. International Journal Of Food Properties13(1), 167-175. doi:10.1080/10942910802256636

Starek, Starek-Swiechowicz (2016) Toxicological Properties of Potassium Bromate. J Pharma Reports 1:122. Retrieved from: on September 30, 2017