Corn Overview

photo provided by the NGCA

Corn, Zea mays L., also known as “maize” is a member of the plant family of grasses. It is grown around the world and is one of the world’s most widely used food staples, third to rice and wheat.

In the U.S., it is one of the most widely grown commodities, accounting for 90% of the total value and production of feed grains. Corn is directly used for livestock feed and food consumption or processed to make food or feed ingredients or industrial products such as ethanol. Currently, there are over 4,200 different uses for corn and corn products in the U.S.

Over 90% of the starch Americans use is produced from corn while corn sweetners such as high corn fructose syrup and others supply more than 56% of the U.S. nutritive sweetner market.

Approximately 36% of the corn crop is fed to livestock, 27% used for ethanol production, and 13% exported to other parts of the world which accounts for about 44% of the world export market.

A Closer Look at the Composition of a Corn Kernel

The Pericarp is the outer covering that protects the kernel and preserves the nutrient value inside. It resists water and water vapor—and is undesirable to insects and microorganisms.

The Endosperm accounts for about 82 percent of the kernel’s dry weight and is the source of energy (starch) and protein for the germinating seed. Starch is the most widely used part of the kernel and is used as a starch in foods—or as the key component in fuel, sweeteners, bioplastics and other products.

The Germ is the only living part of the corn kernel. The germ contains the essential genetic information, enzymes, vitamins and minerals for the kernel to grow into a corn plant. About 25 percent of the germ is corn oil —the most valuable part of the kernel, which is high in polyunsaturated fats and has a mild taste.

The Tip Cap is the attachment point of the kernel to the cob, through which water and nutrients flow—and is the only area of the kernel not covered by the pericarp.

Corn Types

There are several types of corn grown around the world but only two major types in Georgia, field corn and sweet corn. Field corn (or dent corn) accounts for 99% of all the corn acreage in the U.S. Field corn is typically yellow though some white is also produced and used specifically in the food market. Sweet corn is what consumers purchase fresh, frozen or canned for eating. It is consumed as a vegetable and is picked when immature. It is sweet to the taste and is produced from hybrids that are specifically developed to have a higher sugar content than regular field corn.

Other types of corn are flint (typically tropical), popcorn, ornamental (usually a dent type that is a mixture of colors) and waxy. Flint corn is distinguished by a very hard outer shell and kernel though it may be used similarly to dent types. Some ornamentals may also be of a flint type. Pop corn is a type of flint corn but has a starchy center that when heated will pop or explode. The moisture inside the starch (which is trapped by the hard exterior shell) turns to steam and builds up enough pressure to cause the kernel to explode exposing the white starchy mass. Kernels of popcorn are much smaller than field or sweet corn types.

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