The Power of Flour
- Donna Morrissey
- Jan 29, 2022
- 4 min read

A Versatile Pantry Staple
Flour is one of the most fundamental ingredients for a bakery.
The amazingly wide range of flour varieties allows bakers to choose flours based on an equally wide range of qualities: low protein, high protein, coarse grind, finely ground, wheat, rye, barley, gluten-free, and more.
Easily, I could write twenty or more blog posts exploring the various types of flours, and perhaps I eventually will, but for this post, I want to focus on how the most common and commercially available flours are processed, and why I think that matters. To learn more about the nutritional qualities of various flours, links to several excellent resources are included at the end of this post.

Bleached and Bromated Flour
By far, the majority of commercial flours milled in the U.S. are bromated, bleached flours, particularly the bulk flours purchased by restaurants, food services, and bakeries. So, what is meant by these terms?
Both terms mean the flour has been chemically treated to help speed up the aging process and to improve how the flour functions in baking. Both processes, particularly bleaching, also makes the flour appear whiter.
Bleaching is typically accomplished by using agents such as benzoyl peroxide or chlorine gas. By themselves, both of these agents are highly toxic. When incorporated into food processing, the chemicals are mixed with neutralizing agents to produce the desired effects while also reducing the toxicity. The time it takes to complete the process also neutralizes these agents, so they are undetectable in the finished product.
Bromated flours are treated with potassium bromate, which is a chemical oxidizing agent. In simplest terms, oxidation means the changing of a chemical structure by adding oxygen. Rust is a good example of oxidation that most people are familiar with; however, this doesn't mean potassium bromate is making rusty flour.

The fact is that flour cannot be used immediately after it's been milled—ok, it can be used, but not if you want it to do anything useful in your baked goods. Instead, flour must be aged first in a process that exposes it to oxygen, which helps change the flour's chemical structure (oxidation) so that it can create stronger protein bonds (gluten) resulting in a more pliable product with greater elasticity.
Aging flour can be done one of two ways: 1) age it naturally by exposing it to open air for oxidation; or 2) throw in some potassium bromate to speed up the process.
The problem with using potassium bromate is that lab studies on mice have linked it to cancer of the thyroid, kidneys, and other organs*. As a result, Europe, Canada, and other countries banned potassium bromate as a food additive, and it carries a warning label in California. The FDA, however, continues to approve its use in the U.S. as a "generally recognized as safe" (GRAS) product.

The reason the FDA awarded potassium bromate a GRAS designation is because the process of baking neutralizes this agent and renders it harmless. It is not/should not be present in the final product. The reason other countries banned its use is because if a product is underbaked, the bromate is not neutralized and could be found in measurable quantities in the finished product.
In the world of commercial baking where baked goods are made in large, commercial ovens, potassium bromate should not be that much of an issue. Commercial bakeries are fanatical about consistency, so oven temperatures, baking times, and internal temperatures are all highly regulated. It is unlikely that a commercial bakery will produce an underbaked product.

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