Sweet corn, which is harvested while still immature, is the type consumed as vegetable. It can be cooked in several ways: on the cob or with the soft kernels removed and served fresh or frozen or canned for future use.
Corn is high in starch and protein, but it lacks 2 essential acids: lysine and tryptophan; as a result, it is not a suitable protein substitute. When corn is consumed along with beans and other legumes, it provides a complete protein.
Corn is a good source of folate and vitamin B1 (thiamine). It also contains a fair amount of vitamin A and C, potassium, and iron. Most of the niacin in corn is in the form of niacytin, which is not broken down in the human digestive tract.
POPCORN
A popular snack food, popcorn is a special variety that grows on a cob smaller than those of sweet or field corn. As the kernels are heated rapidly, the moisture inside them is converted to steam. When the steam pressure builds to a certain point, it bursts the outer shell and the interior turns into a fluffy mass of starch and fiber many times larger than the original kernel.
A cup of air-popped plain popcorn has only 30 calories, making it an ideal high-fiber snack. Popping the corn in oil and adding a tablespoon of butter, however, raises the calorie content more than fivefold, to about 155 per cup.