Why you pack or shake down flour after spooning it into a measuring cup?

You pack or shake down flour after spooning it into a measuring cup to ensure accurate measurement.

Here's why:

* Flour settles: Flour is light and airy. When you spoon it into a measuring cup, there are air pockets between the granules. This leads to an inaccurate measurement, with more air than flour.

* Packing or shaking compacts the flour: Packing the flour with a spoon or gently shaking the measuring cup removes those air pockets, leaving you with a more accurate measurement of pure flour.

Think of it like this:

* Spooning: You're measuring flour *by volume*, but the air pockets add extra volume you don't want.

* Packing or shaking: You're essentially measuring flour *by weight*, because the extra volume is removed.

Important Note: Most recipes are designed for packed flour measurements. If you use un-packed flour, you may end up with a recipe that is too dry.

Always check the recipe instructions: Some recipes may specifically call for "scooped and leveled" flour, which means you scoop the flour into the cup, then level it off with a straight edge, without packing.