What Exactly Is Bromated Flour Anyways?

If you've ever spotted the term "bromated flour" on an ingredient list, you should know that it doesn't refer to a type of flour (for example, whole wheat versus white flour, or types like cake or pizza flour). Rather, it refers to a chemical additive, and it's a little controversial, to say the least.

That additive is potassium bromate, and the idea of adding it to flour was patented in 1914. It's added to bread as an oxidizing agent that makes dough springier and stronger. Specifically, in "regular" (non-bromated) dough, the gluten proteins hang loose, while potassium bromate makes those loose ends connect together, building a network of gluten connections that makes for a more elastic dough. It also makes the dough retain gas, which leads to final baked products with a bigger volume, and it can make the bread fluffier and softer. It's a bit like working with an aged or matured flour (the aging causes the same gluten connections to form), but normally, aging flour would need weeks to oxidize, while potassium bromate does it in less time — and cheaply. Potassium bromate also bleaches flour, making for whiter baked goods.

So, this pretty much answers why people would want to use bromated flour: It provides consistent baking results at scale, plus it speeds up the flour maturation process. It tends to be used more by commercial bakers and for doughs like pizza and bagels (not cakes, for example, as you don't generally want strong gluten bonds in cake batter).

Of course, there's a downside. The big issue is that potassium bromate is considered a carcinogen, that is, it's believed to potentially cause cancer, and it was linked to kidney and thyroid cancers in rats during scientific studies. Because of this, you won't even encounter bromated flour in many parts of the world: Numerous countries have banned it, including the entire European Union, Canada, India, and Brazil, with the first bans starting in 1990. Yet the U.S. Food and Drug Administration has shied away from a ban.

The FDA's rationale is that potassium bromate effectively gets baked out when bagels or pizza cook, reducing it to low levels that are safe for humans. However, that doesn't apply if too much of it is added to a dough, or if the baking time is too short or at too low of a temperature. In such cases, there could still be unsafe amounts of it in your bagels or bread.

That said, bromated flour isn't ubiquitous in the U.S. In California, such flour has to have a cancer warning, so many bakers ditched it, and the state has a ban starting in 2027. In New York, a ban passed but needs to be signed by the governor. Some artisanal bakeries also actively shun it. If you want to avoid it at the supermarket, just stay away from packages that say "bromated flour," or check the ingredients list for potassium bromate.