ENERGY
GIVING FOODS
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MAIZE
Maize is also known as Corn. 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 |
5.0 |
70.3 |
| 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.
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