Consider the measuring cup. As you know, a cup is a convenient way to measure liquids like water or milk or wine. But it is not so convenient for solids like beans, cranberries or flour. And yet in the U.S. most recipes call for flour measured in cups.
The reason for this are historical and somewhat political according to Bee Wilson in her delightful book Consider the Fork. After the French set out in 1793 on an expedition to measure the length of the Earth’s median, they took one 10 millionth of that measure to be the length of one meter. (It turned out it was just slightly off, but very good for the time.) The standard meter was agreed upon in 1889.
Obviously the British and Americans wanted their own non-French measures, and the British adopted, for a time, the Imperial system of measures, including pints, pounds and gallons. Not to be outdone, the Americans chose an even older gallon/quart/pint/cup measure as their standard.
Today the metric system has been adopted by nearly every country in the world other than the U.S., Myanmar and Liberia.
But what about that cup? It is a volume measure, and flour varies a lot in volume depending on how it’s packed.
We took out our inexpensive Ozeri kitchen scale (it cost $15.95) and decided to weigh the flour in a cup of flour. But how to measure it?
When Fanny Merritt Farmer wrote her original Boston Cooking School cookbook, she emphasized that you scoop out the flour and then level off the cup with a knife to make a level cup measure.
That’s one way, but what about sifted flour? Lots of baking recipes call for sifted flour, and while it is intended to remove lumps, it also aerates the flour significantly, and a cup of sifted flour weighs quite a bit less than a cup of flour scooped from the canister.
And finally, some cookbooks suggest that after sifting the flour, you should spoon it into the cup to avoid recompressing it. Here is what we found:
- 1 cup scooped flour – 5.05 oz (143 g)
- 1 cup sifted flour – 4.45 oz (126 g)
- 1 cup spooned, sifted flour 4.13 oz (117 g)
As you can see, a cup of sifted flour weighs almost 12% less than a cup of scooped flour, and the spooned, sifted flour about 18% less. This is a huge difference in a baking recipe!
We tried these same measurements on a more expensive Weight Watchers kitchen scale. It’s more durably made (and costs 3-4 times as much). It also allows you to convert food weights to Points Plus values, but it gets exactly the same results.
So what do you do?
First, you need to recognize that there is a huge difference in the amount of flour you use depending on whether it is sifted or not when you cooking.
But should you use a scale in the kitchen? It is surely easier to use if you are adapting recipes from other countries. And the recipes in Modernist Cuisine are all in grams. But for American recipes couched in cups, you really have no idea how many grams of flour they mean.
It’s also way easier than sifting the flour to get the right amount. Just weigh out 126 g and you’re done! This is the way we do it now. It’s so much faster.
Mostly, it is important that you are consistent in your techniques and regard the measuring cup as an aliquot rather than an absolute measure. If you repeat the recipes the same way every time, it really doesn’t matter how many grams of flour you are using. Just remember that “sifted” flour means “less” flour.
Food Science Institute 