What's the purpose of sifting flour?
Dear Straight Dope:
Why do recipes tell you to sift flour? I think it's a pain in the ass, it wastes time and makes a mess. The stuff I buy at the store claims to be pre-sifted, but I can tell that it's denser before I sift it than after, so the measurements would be off. If it's just a matter of "fluffing" the flour to make it measure right, why don't they just adjust the quantities in the recipe and have you measure-then-sift instead of the other way around? Then us lazy butts could skip the sifting step and let our electric mixers do all the work.
There are several reasons to sift flour. 1) Flour will compact during storage & handling, but it will not compact at the same rate. 2) sometimes it's lumpy (usually not a problem with modern flour). 3) Sometimes it has additional random protein (insects) (again, usually not a problem these days). 4) Sometimes you have to sift ingredients into flour. Most bread recipes (that I've read, anyway) call for so many cups of flour to be mixed in, and then you're supposed to add more flour, in small increments, until the dough feels right. I don't sift flour for bread, unless it's really lumpy. If I were to bake a cake from scratch (HA!) then I would sift the flour. And I'd use real cake flour, too. If I wasn't institutionalized by then.
Oh, yeah, it also gives you that "I'm a REAL COOK" feeling to sift flour.
SDSTAFF Jill adds:
I gave up sifting flour a long time ago, when I watched a friend of mine, a professional cook, make a cake and simply stir the dry ingredients with a wooden spoon. Yeah, you wouldn't want to bite into a hard chunk of baking powder, so I guess sifting would eliminate that possibility. I don't think it's necessary, with modern ingredients. If your flour or baking powder has hard chunks in it, need to buy new stuff.
SDSTAFF Lil chimes in with:
Do modern recipes ask you to sift the flour? Just about anything I make, (which isn't much), is from my grandmother's cookbook and recipe box. Anyway, I like sifting the flour. I have an old-fashioned metal sifter that was my grandma's, the kind that you turn the handle like a jack-in-the-box. It makes a big cool looking pile of flour that's silky feeling like baby powder. I think it's fun, anyway, even if it is useless.
SDSTAFF Lar authoritatively ripostes:
I don't have as much interesting stuff to add to this as I thought I did (story of my life). Lynne has covered the bases pretty well. The only thing I have to contribute is that Rose Levy Beranbaum (author of The Cake Bible) says that the main reason for sifting is to separate and aerate the flour particles to make them absorb liquids better. Also, sifting does make measuring flour more even although of the sources I consulted one claimed that a cup of flour weighs 5 oz. and the other claims a cup of flour weighs 5.6 oz. If someone would put all this together into a real answer I'd be grateful but if not I'll try to get it done just as soon as a write a kick-ass answer about tie-dying.
SDSTAFF Ed concludes:
Naah, I'm going to leave it like this. It's more in keeping with the kaffeeklatsch nature of the enterprise. And you guys think investigative research is all lab beakers and trenchcoats, eh?