There are five general kinds of corn, each characterized by a different endosperm composition. It appears that a high-protein popcorn type was the first corn to be cultivated, but all five were known to native Americans long before the coming of Europeans.
- Popcorn and flint corn have a relatively large amount of storage protein that surrounds granules of high-amylose starch.
- Dent corn, the variety most commonly grown for animal feed and for milled food ingredients (grits, meals, flours), has a localized deposit of low-amylose, “waxy” starch at the crown of the kernel, which produces a depression, or dent, in the dried kernel.
- Flour corns, including the standard varieties of blue corn, are soft and easily ground because their endosperm is a discontinuous and weak combination of relatively little protein, mostly waxy starch, and air pockets. What we call Indian corn today are flour and flint varieties with variegated kernels.
- Sweet corn, a popular vegetable in the United States when immature, stores more sugar than starch, and therefore has translucent kernels and loose, wrinkled skins (starch grains reflect light and plump out the kernels in the other types). Most corn-producing countries also eat immature corn, but use the other general-purpose corn types. The native Americans who first developed it apparently enjoyed sweet corn for its full flavor when parched.