Cake flour is a type of wheat flour that is very fine and, as such, is particularly well-suited to cakes, cookies, and other confections that need to have a light and fluffy texture. It is related to the more standard “all-purpose” flour, but is more processed — and in many cases, is actually made from a different part of the original wheat germ. The result is a silky, powdery substance that is low in protein and does not typically bind much with other ingredients.
Texture is the main thing that sets cake flour apart from other varieties. It is often milled so fine that it is actually soft to the touch, much like baby powder or powdered sugar. Most of the time, it is pure white as well, thanks to the intensive bleaching process it goes through as it is made.
Cake flour is often more expensive than other, more standard types of flour and is usually sold in smaller quantities. Though many different brands produce it around the world, there is usually little difference between true cake flours. The most important characteristic is the fine grind, which allows baked goods to set up differently than they would with a thicker product.
Milling and Manufacturing Process
Getting wheat to such a refined point is often a rather involved undertaking. Millers first isolate wheat germ’s endosperm, which is the softest part of the kernel. The endosperm is set aside and ground specially into a powder, which is then heavily bleached. Bleaching not only produces a uniform color, but it also helps break down the wheat’s inherent protein.
Wheat is not usually considered a “high protein” food, though it does contain a number of linked protein molecules. These don’t really translate into much dietary benefit, but they do have an effect on how the product interacts with other ingredients and sets up. So-called “high protein” flours are also high in gluten, which leads to dense baked goods. Bread flour, for instance, has a protein content of about 15%; cake versions are usually closer to 7%. Without so many bonds between wet and dry ingredients, batter and dough set up much differently. While by no means gluten-free, cake flour has much weaker glutinous bonds and tends to create airier, fluffier products.
Why Cooks Choose It
The fine grains also absorb fat readily, ensuring that butter or oils are well distributed throughout the batter. Cake flour may also have a high volume of sugar when compared to higher protein flours, which makes it particularly well suited for dessert confections and may require cooks to add less refined sugar overall. Much of this is owing to the endosperm, which often contains comparatively high levels of natural sweetness.
Far and away the main reason why most cooks choose this more refined product is because certain recipes call for it. Specialty cakes, cookies, and other foods that are designed to be made with cake flour often don’t turn out as well if they are made with coarser, more protein-laden alternatives. Cakes don’t crumble as nicely, for instance, or may simply taste “heavy.” They also may not rise out of the pan as much during cooking, leading to an end product that is not particularly pretty to look at.
Home chefs who do not have ready access to cake flour can usually achieve similar results with a few alterations to standard all-purpose flour — though straight substitutions rarely work out. Most experts recommend a combination of all-purpose flour and cornstarch which, when blended and heavily sifted, often leads to a similar final product. One of the most common substitutions instructs cooks to remove 2 tablespoons (15.62 g) of flour from each cup (125 g) that the recipe requires, replacing them with ordinary cornstarch. The mixture must then be sifted between six and ten times to ensure a good blend and to help weaken the heavier flour’s consistency.
Care and Storage
For the most part, caring for cake flour is no different from caring for any other sort of flour. It's best to store it in an airtight container, as this will prevent excess moisture from building up. Cooks should also use it up within about a year for the best results. Flour doesn’t really expire in any real sense, though it will lose its potency and freshness over time. It is sometimes possible to extend its lifespan by refrigerating or freezing unused portions, though professional cooks often debate whether this does more harm than good. Cold storage may preserve the flour, but it can also cause it to dry out prematurely. A lot depends on the storage mechanism and the precise temperatures at issue.