Are they really that different?

By Corey Williams
May 20, 2019

If you’ve ever found yourself staring blankly at the rows of seemingly identical (but somehow impossibly different) bags of flour in the baking aisle, you’ve probably wondered: “What the heck is the difference between bleached and unbleached flour?” You’ve come to the right place.

How Is Flour Made?

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Flour can be made from a variety of plants (see: "A Practical Guide to Alternative Flours"), but you’re likely most familiar with wheat flour. Flour is made by milling wheat grains into a fine powder.

People have been producing flour for more than 6,000 years. Early civilizations likely used stone, or a mortar and pestle, to grind the grains. We now have technologically advanced flour mills, but the process remains essentially the same.

Bleached vs. Unbleached Flour

Elizabeth Laseter

You might be surprised to learn that flour is a pale yellow color when it’s first milled. It’s actually the aging process—and exposure to atmospheric elements—that turns the flour white, usually after a few months. Aging doesn’t just affect the flour’s color—aged flour bakes better, too.  

On Food and Cooking author Harold McGee notes that “aging affects the bonding characteristics of the gluten proteins in such a way that they form stronger, more elastic doughs.”

So … wait a minute: If flour turns white naturally over time, what’s the point of bleaching it?

Bleached flour is simply flour that was aged chemically (usually with peroxide) to speed up the process, rather than naturally over time. Benzoyl peroxide (yes, that benzoyl peroxide—the one from your acne cream) is one of the most commonly used bleaching agents during flour processing.

Unbleached flour, meanwhile, has been naturally aged after being milled. That’s not to say it hasn’t been treated with chemicals—potassium bromate is often added—but it usually has been treated with fewer chemicals.

Is Bleached Flour Bad for You?

Maybe, maybe not. The European Union, Canada, and China have banned peroxides in flour processing because of health concerns, but American manufacturers can still use them. It’s up for debate how ingesting small quantities of peroxides can affect your health in the long run, but the bleaching process does cause the flour to lose a lot of nutrients—namely protein and calcium. Do with that information what you will.  

When Should You Use Bleached Flour?

Photo: Aaron Kirk; Prop Styling: Heather Chadduck; Food Styling: Pam Lolley

Bleached flour is slightly softer than its unbleached counterpart. Foods made with bleached flour tend to be softer and have more volume than those that aren’t. It can improve the texture of soft baked goods like cookies, cakes, quick breads, muffins, etc.

Try these recipes:

When Should You Use Unbleached Flour?

Photo by Rebecca Firkser

Unbleached flour is denser than bleached flour, so it works well for sturdy desserts like pastries. Note: Unbleached flour takes longer to produce, so it is typically more expensive than bleached flour.

Try these recipes:

Does It Really Make a Difference?

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Yes, choosing one flour over the other can have a very subtle effect on how your recipe tastes. Should you lose sleep over it? Probably not. The differences will be so slight, only someone with a very refined palate will be able to detect it. In the end, it’s all about personal preference.

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