Hailie asked: “If a recipe calls for corn flour, can I use cornmeal?”
In 2021, 92 million acres of land in the U.S. were planted with corn. That’s 143,000 square miles, more than the size of Germany. And only a small fraction of that is the sweet corn we eat on the cob; almost all of it is other varieties destined for drying, such as dent corn, flint corn, and popcorn. No wonder there’s a plethora of dry-corn-derived products.
Cornmeal is ground from dried corn. Generally it’s ground fairly fine. You can make it into cornbread or corn muffins, or dust the underside of your homemade pizza with it.
Cornstarch is made by extracting and purifying just the starch portion of the corn kernel; the protein and oil that remain are used for other things.
If you read a British or Irish cookbook, you may be confused by the fact that what we call cornstarch, they call “corn flour.” In the States, corn flour is just dried corn that’s milled finer than cornmeal, to a flourlike consistency.
Corn grits, like cornmeal, are ground from dried corn kernels; typically coarser than cornmeal, and intended to be cooked into a delicious buttery porridge. Instant grits are precooked so they soften faster. (Are there non-corn grits, asked my editor? Yes, rice grits, a.k.a. Mississippi middlins, are great.)
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Polenta is the same idea; coarse-ground corn that you cook into a porridge. You can substitute grits for polenta and vice versa, but polenta is traditionally made from a different variety of corn: where grits (and cornmeal) are made from dent corn, polenta is made from flint corn, which has a harder starch kernel. As a result, polenta retains a little more bite and coarse texture when it’s cooked.
Flint corn is also typically nixtamalized: cooked in an alkaline solution to soften it, free up its nutrients, and develop the familiar corn-tortilla flavor. It’s then made into products like corn tortillas, chips, and masa harina, a flour from which you can make your own tortillas. The whole nixtamalized corn kernels, which are essential for posole, are known as hominy.
Confusion warning: In the South, grits used to be commonly made from those nixtamalized kernels, but, although contemporary grits are usually made from untreated corn, you still hear them referred to as “hominy grits.”