Sifting

• Sifting flour is simply putting it through a fine mesh sieve to remove larger particles or break up clumped pieces. To sift flour, scoop it into a sifter with a mesh bottom and shake until all of the flour falls through. Flour can disperse and be messy when it falls through and should be sifted into a larger bowl, preferable one that can hold the whole sifter.

Aerate Flour

• For many recipes that call for sifting it does not make much of a difference if the flour is sifted or not. Sifting the flour will incorporate air into the flour and make it lighter. Baked goods such as biscuits and cakes can benefit from sifted flour because the liquids added are absorbed evenly by separated particles of aerated flour. When baking cookies and breads that are already quite dense, sifting doesn't really make a difference in how the baked goods come out.

Mixing Dry Ingredients

• Sifting is also used in recipes to mix dry ingredients together. If there are just a few ingredients sifting might not make much of a difference. A recipe that calls for a large amount of flour to be sifted with a little sugar and salt will most likely turn out fine without sifting. When very fine powders like baking powder and powdered sugar are mixed with flour, sifting can be beneficial to evenly distribute the ingredients together and avoid clumps of any one ingredient.

Accurate Measurement

• Recipes distinguish between sifting the flour before or after measurement because the reading will be different when flour is sifted. Flour that has settled together and clumped in a bag will measure differently than sifted flour. A cup of flour, sifted calls for sifting after measurement while a sifted cup of flour is sifted before measurement. The most accurate measurement of flour is by weight.