Flour is a kitchen staple, and we use it in a variety of ways, from baking breads, cakes, cookies, and biscuits to making roux, sauces, and pastas to coating fried foods. While flours can be milled from barley, chickpeas, and tapioca (just to name a few options), we rely most heavily on all-purpose flour milled from wheat in our recipes. But despite the all-encompassing name, not all “all-purpose” flours are the same. In the test kitchen, we keep two types of all-purpose flour on hand: moderate-protein flour and high-protein flour, and we’ll often note a preference for one or the other in our recipes. We’ve found that these two products sometimes perform differently, and we employ each strategically when making baked goods to produce a desired texture. But what causes these differences, and how can such a simple ingredient create such varied outcomes?
To find out, we took a closer look at all-purpose flour by rounding up five top-selling brands and using them to make our Easiest-Ever Biscuits and Olive Oil Cake recipes. We also had our resident bread expert, Cook’s Illustrated Senior Editor Andrew Janjigian, use each flour to make loaves of our Almost No-Knead Bread. Along the way, we asked tasters to evaluate the appearances, textures, and flavors of the baked goods.
All-purpose flour comes in both bleached and unbleached varieties. When flour is milled, pigments in the wheat called carotenoids (the same pigments that give carrots their bright orange color) give it a yellowish hue. While this color fades to off-white with exposure to oxygen over time, some manufacturers choose to speed up the process by chemically bleaching their flours with additives such as chlorine gas or benzoyl peroxide. While the U.S. Food and Drug Administration considers the chemicals used to bleach flour food-safe, several of these additives are banned in many countries, including China, India, and Brazil, as well as in the European Union.
Many brands make both bleached and unbleached versions of all-purpose flour, but we opted for the unbleached versions here since we’ve found in previous testings that bleached flours sometimes produce a bitter, metallic flavor in baked goods. We did include one bleached flour from White Lily, a favorite brand in the South that does not offer an unbleached version. While we didn’t detect any off-flavors in the biscuits, cake, or bread we made with the White Lily flour, we did notice that the baked goods we made with it were paler in color than those we made with the unbleached flours.
The protein content of wheat flours can range from about 7 percent to approximately 13 percent. A flour with less protein (and thus less ability to form gluten) will produce a tender, soft texture best suited for cakes and desserts, while one with more protein will form more gluten and produce a chewier, more open crumb best suited for breads. The protein content of all-purpose flour usually falls somewhere in the middle of the above range, so it can be used in a wide variety of recipes. To produce flours with different protein contents, manufacturers use specific classes and blends of wheat. Hard wheat, which has more protein, is most often used to make bread flour and all-purpose flour, while soft wheat, which has less protein, is primarily used to make cake flour, but it can be blended with hard wheat varieties to produce all-purpose flours.
When we contacted companies to ask about the protein content percentages of their all-purpose flours, we were surprised to discover a fairly wide range—from 7 percent to 12 percent, with levels on the lower end of the range close to that of cake flour and levels on the higher end close to that of bread flour. Some companies mill their all-purpose flour to a specific protein content percentage that is consistent across all bags (for example, 11.7 percent in King Arthur), while others allow for a range of protein content from bag to bag (for example, Bob’s Red Mill states that the protein content of a bag of their all-purpose flour can range from 10 to 12 percent). To see how much of an impact protein content has on food, we started baking.
The protein contents of the flours didn’t seem to matter when we used them to make cakes. All the cakes were well risen, tender, and about the same size. This is likely because there’s proportionally less flour in cake batter than there is in biscuit and bread dough.
We saw much more variation in the textures and heights of the biscuits and breads we made with each brand. The White Lily flour, which is milled to a protein content range of 7 to 8.5 percent, produced squatter biscuits and bread loaves that were two-thirds as tall as loaves made with other flours. Consequently, the interiors of the baked goods made with White Lily were “soft” and “cakey” due to the lack of gluten structure. While this soft texture was pleasant in the biscuits—one taster remarked that the White Lily biscuit was like “a savory cupcake”—it was unacceptable in the bread.
While lower-protein White Lily produced the most dramatic differences we saw among the baked goods, we still noticed some variation between baked goods made with the higher-protein and moderate-protein flours. All produced perfectly acceptable breads, cakes, and biscuits, but the bread loaves we made with the higher-protein flours were particularly tall and well risen, with an open crumb and chewy texture. If we’re being picky, the biscuits we made with these higher-protein flours were a tad “bready” compared to the more tender biscuits we made with moderate-protein flours, but that’s a small price to pay for the superior bread loaves those higher-protein flours churned out.
While it’s worth seeking out higher-protein all-purpose flour if you bake a lot of bread, moderate-protein all-purpose flours such as those from Pillsbury and Gold Medal work perfectly well in the vast majority of recipes. The bread we made with the Pillsbury flour rose as tall as one of the breads we made with a higher-protein flour, and while it wasn’t quite as chewy, it was still a decent loaf.
Ultimately, the best all-purpose flour depends on how you plan to use it. For that reason, we've decided to forgo our usual chart rankings and list the flours according to their protein contents and provide tasting notes that will help you decide which flours suit your needs and preferences.
In the test kitchen, we’ll still be stocking two types of all-purpose flours, but we realize that, for many home cooks, that may not be an option due to storage concerns. If you bake a lot of bread and prefer stocking only one flour in your kitchen, we recommend buying a higher-protein all-purpose flour such as King Arthur Unbleached All-Purpose Flour or Bob's Red Mill Unbleached White All-Purpose Flour. (While the protein content of the Bob’s Red Mill flour ranges from 10 to 12 percent, we suspect that it’s closer to the higher end of that range based on how it performed in our tests.) The higher protein content in these flours is the key to making the tallest and most airy loaves, and, in our tests, both products also made perfectly acceptable cakes and biscuits.
However, if you don’t bake a lot of bread, we recommend buying an all-purpose flour with a moderate amount of protein, such as Gold Medal Unbleached All-Purpose Flour or Pillsbury Best Unbleached All-Purpose Flour. They are a good option in biscuit, cake, or cookie recipes. And, as our tests proved, they’re also perfectly fine for making the occasional loaf of bread.
As for the lower-protein flour in our lineup, White Lily Enriched Bleached All-Purpose Flour is often lauded by Southern home cooks as the secret to making tender, flaky biscuits. However, we found that we were able to produce perfectly good biscuits with moderate- and higher-protein flours. Unless your primary focus is biscuit making, we recommend stocking your kitchen with a moderate- or higher-protein flour, both of which are much more versatile.