After listening to Evan Kleinman's talk with Cindy Mushet about flour on the Good Food show this past week, we were left thinking about bleached and unbleached flour. Mushet is insistent that unbleached flour is best, and that made us wonder why it started getting bleached in the first place...
Fresh flour straight from the mill isn't actually quite ready to be used in baking and actually improves with a little aging. Harold McGee of On Food and Cookign explains that during the aging time, flour undergoes a chemical process where oxygen in the air reacts with the glutenin proteins (which eventually work to form gluten) to form even longer chains of gluten. This means that doughs made with aged flour will have more elasticity and structure.
Fresh flour is also slightly yellowish to start off with, but then becomes paler as pigments in the flour oxidize during aging. The color change doesn't affect anything chemically within the flour, but was originally an indicator that the flour had been aged for a certain period.
Around the beginning of the 20th century, it became common to use certain chemicals to speed up the aging process, allowing milling facilities to produce more flour and save on storage space. Potassium bromate was commonly used to speed aging, and then bleaches like benzoil peroxide and chlorine dioxide were used to approximate the whiteness of naturally aged flour.
In more recent history, medical concerns have risen over the consumption of potassium bromate, so it has been mostly replaced with ascorbic acid. Although bleaching hasn't been raised into question medically, it does seem to affect the structure and flavor of the flour itself. As Cindy Mushet explained in her interview on Good Food, this makes bleached flour generally less ideal in her opinion.
What do you think - does bleached or unbleached flour make a difference to you?
Related: Good Cure Question: What Are Processed Foods?
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Is all cake flour bleached? I don't use it because I haven't been able to find it unbleached. So obviously, I'm pretty much anti-bleached flour. :)
I think I remember something about adding cornstarch to all purpose flour to approximate cake flour, but I can't remember where.
Great info about flour milling--thanks!
I've used both and never noticed a difference. I buy un-bleached now in hopes that it's a little "greener".
i wonder if you might be able to sub out pastry flour which is available unbleached and has a similar protein content.
Note this old question...
http://www.thekitchn.com/thekitchn/good-questions/good-question-pastry-flour-vs-cake-flour-008151
I discovered long ago that unbleached flours simply taste better than the standard bleached flours (e.g., King Arthur vs. Gold Medal). Maybe this is due to unbleached-flour millers (usually smaller companies) sourcing higher-quality ingredients than the bigger guys, or something like that. All I know is unbleached flour has a much nicer flavor. As a blogging breadmaker (http://www.abreadaday.com), it's important to me! (Apologies for the shameless plug.)
by process of elimination and in consultation with an allergist at Lahey Clinic, I've determined that something in the bleaching and/or bromating process affects flour so that I am allergic -- causing wheezing at times and nasal and sinus troubles (too ugly to describe here) -- as well as occasional skin rashes on the face. I wonder whether any systematic studies have been made to see if there is a casual link between bleached flour and the rise of allergies -- asthma in particular? I doubt it, because the allergist at Lahey was dumbfounded when he had to confirm that my process of elimination diet showed this up.
King Arthur began offering unbleached cake flour several months back.
In response to my questions about the product, a KA rep wrote: "Thank you for your email. We do find that these are equal cake flours, with the exception of the color. While the bleached flour produces a pure white cake, the unbleached cake flour has a creamy off-white color
to it. The protein levels are the same level."
I have not yet used it, but I plan to give it a try shortly. Most of what I have read suggests that off-the-shelf bleached flour performs "better" (more volume, better structure) than unbleached simply because it is already artificially aged. However, I plan to let some unbleached flour age naturally for several months to see how it performs versus both bleached and non-aged unbleached. I hope to have results at the end of the year.