New Uses for Corn
Much of the great genetic variation found in corn has yet to be
exploited. This implies that much of the increase in genetic yield
potential will continue to come from the steady application of
proven breeding principles by breeders through selection of improved
lines from many crosses. Genetic engineering offers new
possibilities for adding genetic traits, but to date most of those
changes have been in defensive or compositional characteristics —
herbicide resistance, insect resistance, increased and improved
nutrient levels, etc. — and not in ways that directly increase yield
potential. Research to identify genes that influence yield and how
they work, and to harness this technology to increase yield
potential is in progress.
Corn as a crop has not changed much in ways that are visible.
Hybrids have improved slightly in harvest index a measure of
efficiency (the percentage of total above-ground dry matter to that
of the grain), the best hybrids have a harvest index of 50 to 55
percent. However, large ears need an adequate stalk for support and
adequate leaf area to fill grain, so harvest index is likely
approaching a maximum that is not a great deal higher than at
present. This means that plants with higher net photosynthetic rates
or longer duration of leaf area will be needed in order for yields
to continue to increase. In Manitoba producers have exceeded 200
bushels per acre in yield test competition. It is thus possible to
project future yields in excess of 200 bushels per acre in the more
favourable growing areas. There are many different types of corn
that vary in physical and chemical characteristics. But the
different types generally differ from one another in only one or two
genes, so that all types generally require similar management
practices.
Hundreds of edible and non-edible products are made from corn and
new uses are emerging rapidly. Physical and chemical processes used
to break down the grain greatly increase the value of the original
product. Wet milling and dry milling techniques are used to separate
components, which are then further processed. Wet milling, with
water and heat, produces cornstarch that is used in industrial
applications (manufacture of paper and adhesives) or as a food
material (thickeners, extenders, corn syrups, and sweeteners). Dry
milling produces corn oil, corn meal (for corn chips, flakes, and
tortillas), and corn grits for brewing. The whole grain is used to
produce whisky, gin and vodka, ethanol production (blended with
gasoline to produce a biofuel) and for manufacturing bioplastics.
Corncobs are used in the production of solvents, abrasives and
absorbents. Cornstarch is an ideal substrate or food for
microorganisms that are used in fermentation processes
(pharmaceutical and industrial chemical production). The starches in
corn can also be converted using chemical techniques into an
assortment of other chemicals. Corn is a domestic renewable resource
with value added properties on processing. Special types of corn
are produced under contract, to earn a premium, the grain must be
kept separate from other types until it is delivered to the market.
Dent and Flint are the principal types of corn. In North America
dent is the principal corn type grown. It is characterized by the
indentation in the crown of the kernel caused by the collapse of the
central core of the endosperm on drying.
Globally, corn is the most widely used energy supplying feed for
livestock, but rations based on corn normally must be supplemented
to improve both the quality and quantity of protein. Dent corn
contains about 9 percent protein, while swine, beef cattle and
poultry rations require 11 and 20 percent protein; this additional
protein must be provided by some other high protein supplement.
Although genetic corn stocks are available that contain as much as
27 percent protein, they generally have lower starch content, which
generally means lower yields. In fact, an improvement in the
protein content of corn may be of little advantage for non-ruminant
animals such as swine and poultry unless the amino acid balance is
also improved. Most of the protein in corn is located in the
endosperm, and this type of protein is low in the amino acids lycine
and tryptophane, both of which are essential in nutrition of
non-ruminant animals such as poultry, swine, and humans. Poultry
rations also need supplementation with the amino acid methionine.
High-Lysine Corn
The term quality protein maize is sometimes used to designate
newer, high-lysine corn that is improved in yield and kernel
characteristics. They have protein with increased lysine content and
are a more complete feed source for livestock. Genetic engineering
are being used to improve the balance of amino acids in corn protein
by altering proportions of different proteins in the kernel. These
new corn types will increase and improve the feed efficiency of
livestock.
High Oil Corn
The increased interest in fat or oil high in
the polyunsaturated fatty acids for human use has been reflected in
the greater use of vegetable oils including corn oil. Normal corn
contains about 4 to 4.5 percent oil. Hybrids with 1 1/2 to 2 times
this amount of oil, and with yields competitive with those of normal
hybrids, are commercially available. Feeding trials with swine and
chickens show that higher oil content increases feed efficiency.
High-oil corn commands a premium in the market, with the premium
often based on actual oil content. Equipment for use in testing oil
(and protein) content at the elevator has been developed to aid in
marketing this grain. More recently in response for healthier corn
oil i.e. reduce trans-fats in food high-oleic or low-linolenic oil
hybrids have been developed.
Low-Phytate Corn
Much of the phosphorus in corn grain is stored in the form of
phytate, which is digested poorly by monogastric animals (pigs,
poultry, man, etc.) and thus passes through the animal. This results
in more phosphorus in the environment, where it can cause nutrient
enrichment that stimulates algal growth and thus lowers surface
water quality. The phosphorus in low-phytate corn is digested more
efficiently, lowering the need to feed supplemental phosphorus and
thus producing less phosphorus in the environment.
White Corn
White corn is the principal corn grown for food processing – corn
flakes, tortilla, and corn meal. Other food types are waxy corn (amylopectin
and amylose corn). Waxy corn is used in industrial processes or for
processing in to edible cornstarch and used as a substitute for
tapioca a product derived from cassava roots. Amylose corn because
of the special properties of the starch, are important in some food
products and industrial processes.
High-Starch Corn
Corn is one of the most efficient crops in converting sunlight
energy into energy that is usable by man and animals. Traditionally
this energy has been used as a feed or food source. But, the recent
rapid expansion of the biofuel industry in North America (Manitoba)
has industry looking for corn with high yields and high starch
content that would yield high quantities of ethanol on
distillation. Genetic manipulation and traditional corn breeding
techniques are being used to develop these new high yielding and
high starch hybrids.
These are examples of the types of dent corn that may proliferate
as genetic engineering makes possible large rapid changes in kernel
composition. Similar changes will also be possible in amino acid
profiles (protein quality) as breeders react to demands for
specialty types of corn. The number of possible genetic combinations
is very large, and it is likely that many such “designer” corns will
be commercially produced in the near future, with opportunities for
producers to capture some additional value by growing such crops.
Flint Corn
Flint corn kernels are hard, smooth, and rounded. They have a
hard, vitreous endosperm layer that surrounds a small center of soft
starch. The ears are relatively long and slender with a small number
of kernel rows. Flint corns were probably grown extensively in North
America in Colonial times but are of little importance today.
Sweet Corn
Sweet corn is harvested when kernels are in the milk stage,
before much starch deposition, and is used fresh or for freezing or
canning. Newer hybrids, especially those for home garden use and
fresh market, usually contain one or more genes that make conversion
of sugars to starch in the kernels very slow. These types tend to be
very sweet, and they retain good eating quality much longer than
older varieties due to the inability to form much starch.
For more information on sweet corn production, please refer to
the following link:
www.gov.mb.ca/agriculture/crops/vegetablecrops/bmz00s07.html
Popcorn
Popcorn is essentially a small-kernel flint type. It is used
primarily for human consumption as freshly popped or as the basis of
popcorn confections. There are two major kinds of popcorn grain —
pearl and “hulless”. Pearl popcorn types and the larger “South
American” types have rounded, flinty kernels that usually are deep
yellow or orange-yellow in color. “Hulless” popcorns, also sometimes
called “rice types”, have pointed, somewhat curved kernels and are
usually white.
Currently, most of Manitoba grown corn is used for feed or for
distillation – whiskey and ethanol (biofuel) production. But with
“Global Warming” it is possible that in the future some of the
specialty corn for industrial and food uses could become important
crops in the province.
| Introduction to Corn Production |
How a Corn
Plant Grows |
Choosing a Corn Hybrid |
Soil, Nutrition and Fertilizers |
Seed Bed Preparation
|
Weed Control |
Diseases and Disorders of Corn
| Insects in Corn |
Trouble-Shooting |
Harvesting and Storage of
Grain Corn
| Corn Stover and Silage |
Marketing Grain Corn |
New
Uses for Corn |
Cost of Corn Production |
|
