Sifting and measuring flour in recipes can cause confusion—should the flour be sifted first, before you measure it? Or sifted after it is measured out? Luckily, these questions can be easily answered. First, let's look at why flour is sifted in the first place.
Reasons for Sifting Flour
Before milled flour became readily commercially available, sifting flour was necessary to separate the flour from any chaff (corn or seed husk) or bugs. But nowadays, flour is refined, and won't contain these unwanted elements. If a recipe calls for sifted flour, it is because the recipe will benefit from a more aerated flour, such as delicate cakes (like angel food) that require a light batter. Sifting flour also assures there aren't any lumps and the flour is a smooth consistency. If the recipe calls for sifting flour along with another ingredient—such as cocoa powder—the purpose is to evenly combine the two before they are added to other ingredients.
When to Sift Flour
The most important thing to remember is that unless the recipe specifically tells you to sift flour, don't sift it. Flour processors these days sift the flour many times before it leaves the plant, so there's no need to sift flour for most recipes. Flour sold these days is ready to use right out of the package.
Knowing whether to sift the flour before or after measuring depends on how the ingredient is described in the recipe. For example, if the recipe says "two cups sifted flour," you should sift the flour into a bowl, and then measure it. However, if the recipe says "two cups flour, sifted," you should measure the flour first, and then sift it. Recipe writing (well, good recipe writing) is all about where the comma is, and the placement of words! Before tackling any home cooking, it is important you understand how to read a recipe.
How to Sift Flour
Obviously, a flour sifter—basically a cup with a strainer at the base—is ideal for doing the job, but if you don't have one of those you can use a strainer. Hold a fine-mesh strainer over a bowl, add the flour to the strainer, and gently tap the side repeatedly until all of the flour has gone through into the bowl. You may need to help the last little bit get through the holes—just move it around with a spoon.
Whether the flour is sifted or not, the most important quality in the flour you use in any recipe is that it is accurately measured. It doesn't matter if the flour is fluffy if you have added too much or too little of it. In most baking recipes, inaccurate flour measurement will ruin the recipe.
There are incorrect and correct ways of measuring flour when adding to a recipe. For best results every time, you need to spoon the flour directly into the measuring cup, mound it on top, and then level it off with the side of a knife. No scooping, tapping, or packing down!