Cake Flour vs All-Purpose Flour: What the Protein Difference Changes
|
Time to read 8 min
Baking Science
Two Bags of Wheat,
Two Different Crumbs
Cake flour and all-purpose flour are both wheat flour, and protein is the gap between them. Cake flour comes from soft wheat and runs low in protein. All-purpose flour blends hard and soft wheat and lands in the middle. That number decides how much gluten forms in the bowl and how the crumb holds together on the plate.
Protein Content Separates Cake Flour from All-Purpose Flour
Protein content is the measure that separates one wheat flour from another. Every flour carries a protein percentage, and that figure tracks how much gluten can form once the flour meets liquid. More protein builds a stronger gluten network. Less protein builds a weaker one.
Cake flour generally falls between 7% and 10% protein. All-purpose flour generally runs between 10% and 12%. Mills publish their own numbers, and the figure on the spec sheet is the one to work from when a formula is tight.
Gluten is structure, so the right amount depends on what the item has to do. A yeast bread wants plenty of it, which is why bread work calls for stronger flour. A layer cake wants the opposite, since a tight gluten network turns a tender crumb chewy.
Cake Flour Is Milled from Soft Wheat and Ground Fine
Cake and pastry flour is milled from soft wheat, including soft red winter and soft white varieties. Those kernels carry less protein than hard wheat and grind down more easily, which is how the flour reaches its fine, powdery texture.
Much of the cake flour sold in the United States is chlorine treated. The treatment weakens the protein further and changes the starch so the flour takes up more liquid, sugar and fat than untreated flour of the same weight. That behavior is what lets a high ratio cake formula carry sugar at or above the weight of the flour and still hold its shape.
Unbleached cake and pastry flour is milled without that treatment, for bakers who want the soft wheat and the fine grind without chlorination. It runs slightly stronger in the mixer, which suits muffins, scones and cake layers that have to stack.
The grind matters alongside the protein. Finely milled flour hydrates fast and disperses evenly through a batter, which keeps the crumb uniform rather than patchy. Cake flour also clumps in the bag, so sifting before weighing or measuring is part of working with it.
All-Purpose Flour Blends Hard and Soft Wheat
All-purpose flour is milled from a blend of hard and soft wheat, which puts its protein in the middle of the range. The blend is the point, carrying enough strength for structure and enough softness for tender results across a wide span of recipes.
That middle position is why one bag handles bread, cookies, pie dough, muffins, pancakes and gravy. It also means mills vary. Two all-purpose flours can sit a full percentage point apart in protein, and the stronger one behaves differently in a cookie dough.
Bleached all-purpose flour has been treated after milling, which lightens the color and softens the flour a little. Unbleached all-purpose flour keeps an off-white color and holds a bit more structure. Both bake well, and the difference in a finished product is small.
What the difference comes down to
Cake flour brings soft wheat, a fine grind and low protein, which produces a fine and tender crumb. All-purpose flour brings a hard and soft wheat blend with mid range protein, which produces structure and chew. Match the flour to the texture the recipe is aiming at.
Cake Flour and All-Purpose Flour Side by Side
| Attribute | Cake Flour | All-Purpose Flour |
|---|---|---|
| Protein content | Roughly 7% to 10% | Roughly 10% to 12% |
| Wheat source | Soft wheat, including soft red winter | A blend of hard and soft wheat |
| Grind | Milled extra fine | Milled less fine |
| Common treatment | Often chlorine treated, unbleached also stocked | Sold bleached and unbleached |
| Gluten development | Limited | Moderate |
| Crumb it produces | Soft, fine and even | Sturdier, with more chew |
| Written into | Layer cakes, sponges, chiffon, cupcakes | Cookies, brownies, muffins, quick breads, pie dough |
| Sizes stocked | 5 lb bags and 50 lb bags | 5 lb bags and 50 lb bags |
Which Bakes Call for Cake Flour and Which Call for All-Purpose Flour
Cake flour earns its place where a light, fine crumb is the goal. Angel food cake, chiffon cake, sponge layers, white and vanilla butter cakes, cupcakes and delicate rolled cookies all gain from the weaker gluten network and the fine grind. White Spray Cake & Pastry Flour is stocked in a 5 lb bag for development and small batch work.
All-purpose flour belongs where the batter or dough has to hold something up. Cookies that should chew rather than crumble, brownies, muffins, quick breads, pie dough and pound cakes loaded with fruit, nuts or chocolate all want the structure that mid range protein provides.
Some cakes sit on the all-purpose side of the line even though they are cakes. A chocolate cake already carries cocoa powder, a fine dry ingredient that softens the crumb on its own, and carrot and banana cakes carry heavy wet add-ins. In both cases the extra protein gives the batter something to hold onto.
Substituting All-Purpose Flour for Cake Flour
Swapping all-purpose flour into a recipe written for cake flour works. The exchange runs one for one by weight, and the cake comes out slightly coarser in the crumb and a little less tender. Many eaters will not flag the difference.
Mixing carries more weight once the stronger flour is in the bowl. Gluten develops with agitation, so a batter built on all-purpose flour wants a short mix that stops as soon as the flour disappears. Overmixing is what turns a slight change in crumb into a tough one.
Cakes built on whipped egg whites are the harder case. Angel food and genoise depend on the batter holding air through folding, and the stronger flour knocks more of that air out, which costs height in the pan.
Making a Cake Flour Substitute with Cornstarch
A cake flour substitute comes together from all-purpose flour and cornstarch. Cornstarch carries no protein, so replacing part of the flour with it pulls the protein content of the mix down toward the cake flour range and tenderizes the result. Cornstarch sits with the rest of the baking starches in most stockrooms.
For every cup of cake flour a recipe calls for, measure a cup of all-purpose flour, remove 2 tablespoons, then add 2 tablespoons of cornstarch. By weight that lands at about 105 grams of all-purpose flour with 14 grams of cornstarch. Whisk the two together and sift the mix, preferably more than once, so the cornstarch spreads evenly and the blend aerates.
The substitute closes most of the gap. It does not reproduce the fine grind of milled cake flour or the liquid and sugar capacity of chlorinated flour, so a production formula is better built on the flour it was written for.
Cake Flour Does Not Hold Up in Cookies and Quick Breads
Substituting cake flour into a recipe written for all-purpose flour causes problems. The dough ends up short on protein, and the structure follows: bars and cakes that sink in the center, cookies that spread thin or break apart when lifted off the sheet.
Liquid is part of it. Lower protein flour takes up less water, so a cookie dough built on cake flour runs stickier and spreads further in the oven. A bit more flour can pull it back, and baking off one or two cookies before committing the batch shows where the dough stands.
A few applications take cake flour outside of cake work without trouble. Shortbread, meltaway cookies and tender scones are built around a crumbly texture, and lower protein serves them. The line falls at whether the item has to support its own weight.
Before a production run: bake one test batch on the flour you plan to buy in volume. Protein specs differ between mills, and between bleached and unbleached lots of the same type, and a single batch is a cheaper place to find the crumb you want than a pallet.
✦ ✦ ✦
Frequently Asked Questions
Can All-Purpose Flour Replace Cake Flour in a Cake?
All-purpose flour stands in for cake flour at a one for one weight exchange, with a crumb that reads slightly coarser. Weighing rather than scooping helps here, since cake flour is lighter per cup and a volume measurement moves the ratio before the batter is even mixed. Keep the mixing short once the flour goes in.
How Much Cornstarch Does a Cake Flour Substitute Need?
Two tablespoons of cornstarch per cup, with 2 tablespoons of all-purpose flour removed first, which comes to about 14 grams of cornstarch against 105 grams of flour. Sifting is the step that gets skipped and matters most, because unsifted cornstarch leaves pockets of starch that bake into pale streaks.
Can Cake Flour Replace All-Purpose Flour in Cookies?
Cake flour on its own leaves a cookie dough without the protein it needs, which shows up as spreading and fragile edges. Blending the two is the workable version: half cake flour and half all-purpose flour lands near pastry flour strength and softens a cookie without giving up the structure.
What Protein Content Does Cake Flour Have?
Most cake flour sits between 7% and 10%, and the spread inside that band is wide enough to matter. A cake flour at the top of the range behaves closer to pastry flour, which is useful in a scone and noticeable in an angel food cake. Mill spec sheets list the figure for each lot.
Does Cake Flour Need to Be Sifted Before Use?
Sifting is worth the minute with cake flour, since the fine particles pack and clump in the bag. Sifting after weighing keeps the weight accurate, and it breaks up the clumps that otherwise survive a short mix and turn up as dense spots in a finished layer.
What Is the Difference Between Cake Flour and Pastry Flour?
Pastry flour sits between cake flour and all-purpose flour on protein, often around 8% to 9%, and it comes from soft wheat the same way cake flour does. That middle strength suits pie dough, biscuits and laminated doughs where layers need to stay distinct. Cake and pastry flours are stocked together for that reason.
Stocking Cake Flour and All-Purpose Flour in a Production Bakery
A bakery running both cake and cookie work keeps both flours in the stockroom, since neither one covers the other's job. Cake flour goes into the layer cakes, sponges and cupcakes. All-purpose flour goes into cookies, muffins, quick breads and pie dough, and it handles the dredging and thickening work in the kitchen besides.
Write the flour type onto the formula card next to the weight. A card that reads cake flour, soft wheat, 50 lb bag tells the next person which bag to pull, and it keeps a stronger flour out of a sponge on a busy morning.
Baker's Authority carries both in bulk and wholesale case quantities across its flour range.