Is Sifting Flour Necessary?

Not usually, says Christine Gallary:

“There are times, however, when certain recipes actually benefit from sifted flour. The flour in cakes with a very light, delicate texture like genoise, angel food, or sponge should be sifted to eliminate and prevent lumps that would weigh down the batter.

“If your flour has been sitting around for awhile and seems very tightly packed, it might also be a good idea to sift it before using it so that you’re not measuring out overly packed cups.”