|
Oats
Corn is also known as Maize. The leafy stalk produces ears which
contain seeds called kernels. Though technically a grain, maize kernels are
used in cooking as a vegetable or starch.
Uses:
Maize has three possible uses: as food, as feed for livestock and as raw
material for industry. As a food, the whole grain, either mature or
immature, may be used; or the maize may be processed by dry milling
techniques to give a relatively large number of intermediary products, such
as maize grits of different particle size, maize meal, maize flour and
flaking grits. The by-products of dry milling include the germ and the
seed-coat. The former is used as a source of edible oil of high quality.
The seed-coat or pericarp is used mainly as a feed, although in recent
years interest has developed in it as a source of dietary fibre. Wet
milling is a process applicable mainly in the industrial use of maize,
although the alkaline cooking process used in manufacturing tortillas (the
thin, flat bread of Mexico and other Central American countries) is also a
wet milling operation that removes only the pericarp. Wet milling yields
maize starch and by-products such as maize gluten, used as a feed
ingredient. The maize germ processed to produce oil gives as a by-product
maize germ meal, used as an animal feedstuff. Some attempts have been made
to use these by-products for humans in food mixes and formulations.
Chemical Composition:
Gross chemical composition of different types of maize (%)
| Maize type |
Moisture |
Ash |
Protein |
Crude fibre |
Ether extract |
Carbohydrate |
| Salpor |
12.2 |
1.2 |
5.8 |
0.8 |
4.1 |
75.9 |
| Crystalline |
10.5 |
1.7 |
10.3 |
2.2 |
5.0 |
70.3 |
| Floury |
9.6 |
1.7 |
10.7 |
2.2 |
5.4 |
70.4 |
| Starchy |
11.2 |
2.9 |
9.1 |
1.8 |
2.2 |
72.8 |
| Sweet |
9.5 |
1.5 |
12.9 |
2.9 |
3.9 |
69.3 |
| Pop |
10.4 |
1.7 |
13.7 |
2.5 |
5.7 |
66.0 |
| Black |
12.3 |
1.2 |
5.2 |
1.0 |
4.4 |
75.9 |
Nutritional Aspects:
Carbohydrate:
The major chemical component of the maize kernel is starch, which provides
up to 72 to 73 percent of the kernel weight. Other carbohydrates are simple
sugars present as glucose, sucrose and fructose in amounts that vary from 1
to 3 percent of the kernel. The starch in maize is made up of two glucose
polymers: amylose, an essentially linear molecule, and amylopectin, a
branched form. As an energy source, it compares favorably with root and
tuber crops, and it is similar in energy value to dried legumes.
Protein
After starch, the next largest chemical component of the kernel is protein.
Protein content varies in common varieties from about 8 to 11 percent of
the kernel weight. Most of it is found in the endosperm. The nutritional
quality of maize as a food is determined by the amino acid make-up of its
protein. In common maize, deficiencies in lysine and tryptophan are evident
but has a high leucine content.
Oil and fatty acids
The oil content of the maize kernel comes mainly from the germ. Oil content
is genetically controlled, with values ranging from 3 to 18 percent. Maize
oil has a low level of saturated fatty acids, i.e. on average 11 percent
palmitic and 2 percent stearic acid. On the other hand, it contains
relatively high levels of polyunsaturated fatty acids, mainly linoleic acid
with an average value of about 24 percent. Only very small amounts of
linoleic and arachidonic acids have been reported. Furthermore, maize oil
is relatively stable since it contains only small amounts of linoleic acid
(0.7 percent) and high levels of natural antioxidants. Maize oil is highly
regarded because of its fatty acid distribution, mainly oleic and linoleic
acids. In this respect, populations that consume degermed maize benefit
less in terms of oil and fatty acids than populations that consume
whole-kernel products.
Dietary fibre
After carbohydrates, proteins and fats, dietary fibre is the chemical
component found in the greatest amounts. The complex carbohydrate content
of the maize kernel comes from the pericarp and the tip cap, although it is
also provided by the endosperm cell walls and to a smaller extent the germ
cell walls. Maize bran is composed of 75 percent hemicellulose, 25 percent
cellulose and 0.1 percent lignin on a dry-weight basis. Dietary fibre
content in dehulled kernels would obviously be lower than that of whole
kernels.
Minerals
The germ is relatively rich in minerals, with an average value of 11
percent as compared with less than I percent in the endosperm. The germ
provides about 78 percent of the whole kernel minerals. The most abundant
mineral is phosphorus, found as phytate of potassium and magnesium.
Vitamins
The maize kernel contains two fat-soluble vitamins: provitamin A, or
carotenoids, and vitamin E. Carotenoids are found mainly in yellow maize,
in amounts that may be genetically controlled, while white maize has little
or no carotenoid content. Most of the carotenoids are found in the hard
endosperm of the kernel and only small amounts in the germ. The
beta-carotene content is an important source of vitamin A, but
unfortunately yellow maize is not consumed by humans as much as white
maize. The maize germ is rich in vitamin E. Water-soluble vitamins are
found mainly in the aleurone layer of the maize kernel, followed by the
germ and endosperm. Variable amounts of thiamine and riboflavin have been
reported. The content is affected by the environment and cultural practices
rather than by genetic make-up. Maize is a good source of particularly
vitamin B12.
However, of the three major cereal grains (wheat, maize, and rice), maize
has the lowest concentration of protein, calcium, and niacin. Diets that
rely heavily on corn may require the consumption of complementary foods to
supplement its deficiency in certain amino acids and vitamins.
Health Benefits of Maize:
• Provides calories as a part of staple diet.
• Prevents hemorrhoids and colorectal cancer as provides good quantity of
fiber.
• Provides good quantity of thiamin and niacin. Thiamin is essential for
nerve health and cognitive function whereas niacin is required for normal
metabolism and skin health.
• Corn is also a good source for pantothenic acid and folic acid.
Pantothenic acid is required for metabolism of all major nutrients in our
body whereas folic acid is required for our development and repair of
genetic material.
• Provides various important minerals like magnesium, phosphorus, zinc,
iron and copper, all of which play important role in one or more functions
of our body.
• Protects our heart and prevents anemia.
• Provides antioxidants to fight against diseases and ageing.
• Lowers LDL cholesterol, blood pressure and blood sugar. Hence protects us
from getting, heart diseases, hypertension or diabetes.
|
