Measuring CupsI recently received this email from a visitor asking,
"If a recipe calls for four ounces of something, how do you know if they mean four ounces on the food scale, or in the measuring cup? What's the difference between dry measuring cups and liquid measuring cups, why would you need different cups, wouldn't they measure the same amount? This may sound stupid, but not to me. Thanks for your time."
I asked my friend Chef Jennifer Field, a graduate of Orlando Culinary Academy, Le Cordon Bleu Culinary Arts School, who offered this response,
"This is a very good question; many people don't stop to consider that there is a difference at all between liquid and dry measures, so good for you! My general rule of thumb is if the recipe calls for 4 ounces of a liquid, use a liquid measuring cup. If the recipe calls for 4 ounces of a dry ingredient, use your scale. Now to your other individual questions:
What's the difference between dry measuring cups and liquid measuring cups?
Dry measuring cups are meant to be filled right up to the top and then leveled off with a straight edge of some sort. Liquid measuring cups generally have a pour spout and are made to be filled to the gradations on the side of the cup (1/4 cup, 1/2 cup, 6 oz, etc.) rather than being filled right up to the top.
Why would you need different cups?
Wouldn't they measure the same amount? Well, for one, measuring a liquid by pouring right to the tippy top of the measuring cup is just asking for spilling and mess. For another, it's really hard to level a dry ingredient (think flour or oatmeal) if it's not right up to the top of the measuring cup.
Also, for liquids, the mantra "a pint is a pound the world around," basically holds true within a couple of wee fractions of an ounce either way. This means that 1 pint of liquid (16 ounces) = 2 cups of liquid, whether that liquid be milk, water, or oil.
With dry measures, pesky settling must be taken into account. I wasn't a physics major, but it's a matter of mass versus weight: depending on how you use your dry measures (do you scoop up a cup of flour or spoon it into the cup? Do you sift first? Do you pack your flour down?) a cup of flour can vary in weight from about 3.5 ounces to about 5 ounces. That's a lot of variation.
My advice is to measure dry ingredients with a dry measure once and weigh the outcome. Use it in your recipe and see if you like the way it turns out. If so, write down the weight of that particular ingredient and use the weight every time that particular ingredient is called for.
For example, the way I fill a one cup measure, all purpose flour weighs 4 ounces. I like how this works in my recipes, so I will use 8 oz. of all purpose flour for 2 cups in a recipe, or 3 ounces of all purpose flour for 3/4 cups in a recipe."
Hope this helps, and thanks for asking such great questions. I bet this will help other folks with the same questions.