The A-B-C’s of Cake Flour


Special occasions of all kinds are cause for cake. Graduations, birthdays, weddings, and parties for hellos or goodbyes almost always call for cake as the centerpiece of the dessert action.

Just about everyone I know likes eating cake. Baking it? That can be a different story.

Fortunately, cake is a pretty broad category, and there’s a range of cake styles that can suit almost any baker’s comfort level. I think my first cake was a pudding cake from the old Betty Crocker cookbook, called “Hot Fudge Pudding.” I still make that cake. Warm, with good vanilla ice cream and the goo from the bottom spooned over it? Oh, yes.

puddingcake2As my culinary career developed, somehow I got into layer cakes. I enjoyed my pastry class at the Culinary Institute of America a lot. When I learned to clean up the top edge of a frosted cake by sweeping my spatula toward myself at just the right 45° angle, it was extremely satisfying.  I relive that moment to this day, with every cake I make.
20121003-173248I’m still learning, though. (I’m at the stage where I know some things, but am realizing there’s so much more that I don’t know, and the deeper I dig the more complicated things can get). The quest? To understand cake flour, and what happens with different flours in the same cake recipe. Here’s the lineup of contenders:

flourlineupBleached Cake →Unbleached Cake Flour Blend→Self-Rising→Unbleached Pastry→Unbleached All-Purpose

Protein: more is better, except for when it’s not. You probably know that different types of flour have unique protein levels. It’s one of the quickest ways to get a bead on how it will bake. More protein = more structure and chewiness, which is good in bread dough, not what you’re after in cake.

That said, the lower protein number should make the best cake, yes? That’s what I set out to discover, making five different (actually seven, if you count the screw-ups) cakes, using the same formula and each of the flours you see above. We’ll get to those results in a bit, but in the meantime, if you’re wondering, here are their protein levels:

Softasilk bleached cake 6.9%→KAF  Unbleached Cake Flour Blend 9.4%→Unbleached Self-Rising 8.5%→Unbleached Pastry 8%→KAF Unbleached All-Purpose 11.7%.

Bleach. Let’s talk.  Before I go down this path, I should tell you I consulted at length with our own Dr. Andrea Brown, who not only reads but can translate scientific journals and milling science papers. After many hours of discussion, it was clear that while man has been grinding flour and baking with it for millennia, on the molecular level, there are lot of things we really don’t know yet. We just know that some things work. Why is still a work in progress.

What does bleach do to flour? Guess what: It depends on the bleach. Different types of bleach are used on different flours. Bleached all-purpose flours can be treated with hydrogen peroxide, benzoyl peroxide, calcium peroxide, or azodicarbonamide. These bleaches take away electrons from gluten’s two components, glutenin and gliadin (a process known as oxidation), and the resulting proteins formed in dough are somewhat stronger as a result.

Oxygen from the air also bleaches flour, but more slowly. The process of aging flour happens as it’s stored in silos, eventually put into bags, and as it makes its way through the supply chain to your door.


Most cake flours are treated with chlorine bleach. Chlorine is much stronger than peroxides, and its interaction with all of the flour’s components (starch, protein, fat) is still being researched. What we do know is that bleached flour is better able to form a matrix that can hold together a high-ratio cake.

softasilkWhat’s a “high-ratio” cake? There are three things to look at in a cake’s formula to determine this. For an excellent exposition of how cake structure works, see this Fine Cooking article by Shirley Corriher.

A high ratio cake meets the following qualifications:

  • The weight of the sugar is about equal (and usually, a bit greater) than that of the flour;
  • The weight of the eggs is roughly equal to the weight of the fat;
  • The weight of the liquid (eggs included) is roughly equal to (or slightly more than) the weight of the sugar.

The texture  of a high-ratio cake is tender, moist, and usually close-grained without being heavy or gummy. Most classic wedding cakes are high-ratio formulas.

At the other end of the spectrum, a genoise such as you find in our Tiramisu or Buche de Noel relies on whipped egg foam stabilized with flour for structure; to be moist it’s brushed with simple syrup. Our Golden Vanilla and Pound cakes are somewhere in between.


Fun to know side note: Cake flour starts with low-protein flour, which means a greater percentage of the flour in your cup is composed of starch. It’s also very finely ground, with a texture that feels silky. (This has more to do with the way the wheat berries shear as they go through the rollers than with any super-special sifting, FYI.)

If you’re trying to determine what kind of flour you have in an unmarked bulk bin, squeeze it and see what happens. Lower protein flours will stick together and make a clump in your hand; higher protein ones won’t. This is one of the reasons cake recipes call for sifting dry ingredients (or whisking them through a strainer). It’s the most effective way to blend them evenly.

So how did the flours do?

layer lineupThe bleached cake flour (6.9% protein) was the tallest of the layers, with a very fine crumb. It was moist without being dense. The unbleached cake flour blend (9.4%) wasn’t as tall, but the crumb was even and fine. The cake was a little more dense, moist, and tasty. Number three, our unbleached self-rising flour (8.5%), was the biggest surprise. It made an awesome cake (I adjusted the recipe, using an equivalent weight of self-rising to match the weight of cake flour that was called for, and leaving out leavening and salt, because those are already in the self-rising bag).

Here’s where things get interesting. Number four in our lineup is our unbleached pastry flour (8%). If low protein makes good cake, what happened here? Dr. Brown and I tossed it around, and it came out that our self-rising flour has a more acidic pH than the pastry. Acid helps the proteins in the recipe’s egg whites set, enhancing the structure and making a higher cake layer.

I’ve had this poor result with pastry flour in cakes several times; it’s not the ingredient of choice for this high ratio cake. The pastry flour layers were the only set I threw out, not even considering giving them out as snacks. The cakes were low, gummy, and just not at all appealing.

When we were testing our Unbleached Cake Flour Blend, we had a similar result. I made what felt like a billion cakes, and then Sue Gray took the formula across the finish line. This was her output from just one day of testing the blend:

sue with white cake

Sue Gray with some of the white cake layers we made when developing our Unbleached Cake Flour Blend.

Last but not least, on the far right is the layer made with our unbleached all-purpose (11.7%). It’s relying on the protein in the flour for more of its structure, so it’s not quite as tender as the cake made with the bleached or self-rising flour; but it still looks good and tastes just fine.

Does the flour you reach for make a difference when you’re going to make a cake? Absolutely. Do you need to buy a box of bleached cake flour to make cake? Depends.

For some bakers, the texture they want can only be achieved with bleached flour. For my money, I’d rather have our Unbleached Cake Flour Blend, or after what I learned with this project, our Unbleached Self-Rising Flour in my cake any day. Self-rising (self-raising in Britspeak) is the most common flour used for cake in England, and I’m now a believer, and will be giving it a spin in more cakes from now on.

I’ve been depending on and getting great results from our Unbleached Cake Flour Blend ever since we developed it. As I said before, there’s a cake out there for every baker, and a lot of choices for flours. If you have a recipe you love and depend on that calls for bleached cake flour, and you’re not in a pinch for time, you might want to try the alternatives I’ve experimented with and see what you think. You may stay with what you know, or maybe you’ll find a new flour friend!


Susan Reid

Susan Reid grew up in New Jersey, graduated from Bates College and the Culinary Institute of America, and is presently enjoying her fourth career after stints in advertising, running restaurants, and teaching at the New England Culinary Institute. She joined King Arthur in 2002 to ...


  1. Lorraine Fina Stevenski

    Susan, I do LOVE King Arthur Unbleached Cake Flour Blend for making cakes. But now that you gave a fabulous tutorial about flour, I will try the Unbleached Self-Rising Flour next. But…you are certainly right…we are ALL learning everyday and that is what is so fun about baking. Who ate all the cakes you made??? Great information and thanks for sharing with all of us.

    1. The Baker's Hotline

      Huh, I’m not sure what happened to the cakes, Lorraine! However, I’m happy to hear that you enjoyed the cakes so much. Happy baking! Jon@KAF

    2. Susan Reid , post author

      Well, the pastry layers went in to the circular file, as I said. I believe the other layers are in the freezer, waiting for their big moment, next time I need a layer cake on short notice! Susan

  2. Elizabeth

    I’m surprised you didn’t use your own brand’s bleached cake flour (Queen Guinevere) for the testing. I have used it in a couple of cakes using KAF recipes for birthdays and everyone said they were wonderful!

    1. Susan Reid , post author

      I’ve relied on Guinevere more than a few times myself; we like to at least acknowledge that other people make flour, too, once in a while…Susan

    1. The Baker's Hotline

      Depends on the cake, Annie. If the recipe has ratios like Susan described, then it may be a good idea to use a cake flour. If the sugar is lower than the flour, you may not need it. Jon@KAF

  3. Kat

    Can you explain the “tried and true trick” of taking one cup of all purpose flour minus two tablespoons and adding in two tablespoons of cornstarch to make cake flour when you don’t have any. How does this stack up against what you’re listing here? I never buy cake flour anymore so I’d be really interested to learn more.
    Hi, Kat. Good question. The simplest thing to do is put the 2 tablespoons of cornstarch in the bottom of your measuring cup, then sprinkle the all-purpose flour you’re using over that until it’s above the cup’s rim; then sweep the excess off the top. It definitely works to lower the overall protein level in the recipe, making it more tender. Susan

  4. Dana A

    I have been reading a lot of articles on cake flour, etc, my problem is it’s easier to compare when you have examples: 1 cup sugar to 2 cups of flour, etc. also, the ratios on using self rising instead of cake or regular flour. Again, measurement examples would help. Thanks, I enjoyed this topic, it does get confusing.

    1. The Baker's Hotline

      Unfortunately, it is much harder to give advice on subjects such as this if you are measuring by volume as one’s cup of flour may not be the same as the next. This would throw off the ratio of flour to sugar and cause a different set of complications. For best results, I would measure your ingredients by weight. Jon@KAF

  5. Mollie

    That’s all very interesting but what about high altitude?
    Hi, Mollie. I don’t know what altitude you’re at, but start with the guidelines on the chart. I can also tell you from having made a bunch of cake at 8300 feet that a couple of tablespoons of Instant ClearJel whisked into the dry ingredients works wonders, helping the cake batter hold on to the water and giving the final product a much better shape and consistency. Susan

    1. The Baker's Hotline

      As the name implies, whole wheat pastry flour is great for pastry (read pie crust here!). It’s also amazing for quick breads like muffins/scones/biscuits, and great in tender cookies or cakes. Check out the (KAF) Whole Grain Baking cookbook at your local library or bookstore and you’ll be inspired to do a lot of baking, using it in recipes you never imagined could still yield soft and tender results with a whole wheat flour. Happy Baking! Irene@KAF

  6. Jaqui Edelmann

    I live at 7300 feet in the mountains. How would I adjust a recipie to make a layer cake that doesn’t sink in the middle?

    1. PJ Hamel

      William, when substituting self-rising flour for cake flour, omit the salt and baking powder in your cake recipe. While there are no guarantees this substitution will work every time, due to varying amounts of baking powder in cake recipes, it should work much of the time. Good luck – PJH

  7. Livingwell

    I almost always use all-purpose flour for my cakes, only occasionally using cake flour for a more tender crumb. Since it sounds like your Cake Flour Blend makes a crumb that is a happy medium between all-purpose flour and that of a cake mix (yuk!), can it be used as a 1:1 sub for all-purpose flour?

  8. Sam

    I have been baking one of the recipes from The Cake Bible. I have used different flours and had problems with the cake collapsing during cooling. The only time it didnt collapse just the dome shrunk to level with the sides was when using bleached cake flour. What in the bleaching stabilizes the cake like that verse using unbleached/unbromated flour? Can I add some cornstarch or instant clearjel to the flour, not to lower the protein but help stabilize it after baking?

    1. Susan Reid , post author

      Sam, bleaching damages the starches in cake flour, and in doing so increases its “carrying capacity”; the ability for it to hold together a higher ratio of sugar and fat. If a recipe calls for cake flour and you substitute something that isn’t bleached, it’s not uncommon to have the results you’re describing. It’s also quite possible that you’re overcreaming your butter and sugar; too much can make for an unstable structure. Beat butter and sugar together until they look white; if you go so far that touching a mound of the mixture makes it collapse, that’s too far. Susan

  9. Janice Fernekees

    I am still confused. I plan on making Italian Cream 3 layer cake for a pot luck Italian Feast. I have never made this cake before and it says to use 2 cups of cake flour. When I went to the store I saw Silk breached cake flour and King Arthur’s unbleached. I don’t know which flour would be best. When I cook, I use King Arthur unbleached all purpose flour. Everything always comes out great. ????? Can you help me decide?

    1. Susan Reid , post author

      Janice, recipes that call for bleached cake flour are usually what’s called “high ratio”; there is a high proportion of sugar and fat. Our unbleached cake flour will give you good results, but they won’t be exactly the same as what a bleached flour will give you. The grain won’t be quite as fine, and the cake might be a little bit more dense. It depends on how you feel about the bleach, I think. Susan

  10. Gloria Arostegui

    Hi!, now I am more confused than ever! I have always used the same recipe in my country, and it is very simple. I am trying to do it here and the cake comes out very dry.
    2 cups of flour
    2 cups of sugar
    4 egg
    1 cup of milk
    175 grs of butter.

    the procedure is the same, bake it at 350 and while it is hot is perfect when it cools it gets too dry. What am I doing wrong, I know it is not the baking time.

    1. Susan Reid , post author

      Gloria, are you using the same measuring cups? And how are you measuring your flour, by weight or by volume? I’d recommend you call our bakers on the hotline (855-371-2253) or chat online with them; that’s a more effective way to get your question answered. Susan

  11. Gloria Arostegui

    Hi!, now I am more confused than ever! I have always used the same recipe in my country, and it is very simple. I am trying to do it here and the cake comes out very dry.
    2 cups of flour
    2 cups of sugar
    4 egg
    1 cup of milk
    175 grs of butter.
    1 traspón baking poder.
    the procedure is the same, bake it at 350 and while it is hot is perfect when it cools it gets too dry. What am I doing wrong, I know it is not the baking time. Should I sift the unbleached self rising flour?

  12. Pam Powell

    Is it possible to substitute your Cake flour for All Purpose flour in a quick bread recipe? What would the results be? it seems like when I use All Purpose flour in quick breads it’s always so heavy.

    1. Susan Reid , post author

      Pam, I think using cake flour for all purpose would have the opposite effect of what you’re looking for. There are a couple of things to check first. How are you measuring your flour? How old is your baking powder? Susan

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