Biology Reference
In-Depth Information
respectively, in these regions, but this masks
significant variation and per capita food con-
sumption of maize. In Mesoamerica, annual
maize consumption exceeds 80 kg per capita in
Guatemala, Honduras, and El Salvador, rising to
125 kg in Mexico. Maize is also the most impor-
tant cereal food crop in sub-Saharan Africa,
where consumption levels exceed 130 kg per
capita per year in Lesotho, Malawi, and Zambia.
The highest amounts of maize consumed are
found in southern Africa, at 85 kg/capita/year as
compared to 27 in East Africa and 25 in West
and Central Africa (Shiferaw et al. 2011). In
South and Southeast Asia, where direct maize
consumption on an annual average is estimated to
be only 6 and 16 kg per capita, respectively, there
are several areas (especially in the highlands and
tribal regions) where maize is consumed directly
at much higher rates. Maize is also used as ani-
mal feed and raw material for industrial use. In
industrialized countries, a larger proportion of
the grain is used as livestock feed and as indus-
trial raw material for food and non-food uses.
On the other hand, the bulk of maize produced
in developing countries is used as human food,
although its use as animal feed is increasing.
Maize kernels provide many macronutri-
ents and can also provide small amounts of
micronutrients such as vitamins (provitamin A,
vitamin E) and minerals (iron, zinc). The typical
composition of the maize kernel is 8-10%
protein, 3.5-4.5% oil, 1.5-2.0% ash, 1.5-2.1%
crude fiber, 1.4 -2% soluble sugars, 10-15%
water, and 65-70% starch. The endosperm
contains all of the starch and about 70% of the
protein. The remaining protein and high levels
of oils are found in the germ. Fiber and ash are
predominantly in the pericarp (Nuss and Tan-
umihardjo 2010). Maize can also be considered
one of the cereals with a large and diverse set of
nutraceutical compounds. Nutraceutical food,
or functional food, is defined as containing
chemical compounds that exert a positive effect
on human health (Serna-Saldivar 2011). These
chemicals are not considered nutrients that are
normally associated with deficiencies, but they
do play an essential role combating oxidative
stress, chronic diseases (obesity, diabetes), and
cancer (Wildman 2000). The main nutraceuticals
found in maize are phenolics, such as antho-
cyanins and flavonoids (blue maize), carotenoids
(yellow maize), along with phytosterols, fiber,
unsaturated lipids, and folic acid. Even so,
overdependence on maize-based diets without
other complementary food sources may lead to
nutritional deficiency-related diseases, such as
kwashiorkor, anemia, and corneal blindness.
Micronutrient malnutrition alone affects more
than 2 billion people, mostly in resource-poor
families in developing countries. For exam-
ple, more than 300 million people in India
suffer micronutrient deficiencies, and 35% of
the world's malnourished children live in that
country. Protein-energy malnutrition (PEM) is a
potentially fatal body-depletion disorder, which
is the leading cause of death in children in
developing countries. Maize cultivars that com-
bine high grain yield with balanced amino acid
composition, enhanced levels of provitamin A,
and kernel zinc concentration will have a posi-
tive impact on nutrition, health, and the quality
of life, especially in areas where poverty and
low incomes limit access to diversified diets,
dietary supplements, or fortified foods (Ortiz-
Monasterio et al. 2007; Pfeiffer and McClafferty
2007).
“Biofortification” is the breeding of staple
food crops to increase micronutrient density.
Graham and colleagues (2001) suggested that
because of the widespread consumption of sta-
ple crops, biofortification may be an effective
and sustainable way of addressing micronutri-
ent malnutrition. An important advantage with
respect to biofortified crops is that the recur-
rent costs are low and the benefits can be made
available to all developing countries around
the world. The biofortification approach gen-
erally involves a set of one-time fixed costs in
developing breeding methodologies, introgress-
ing nutritional quality traits into elite germplasm,
and adapting these varieties to diverse envi-
ronments. Some researchers (e.g., Bouis et al.
Search WWH ::
Custom Search