Protein.
In
addition to varietal difference, protein content is affected by environmental conditions such as oil and nitrogen fertilizer
application. Protein is mainly distributed the bran and
peripheral of the endosperm. The central part of
the rice grain only contains has small portion of the proteins. Rice protein
has all essential amino acids, in rather a well-balanced
proportion for human body (USA Rice Federation 2002). The protein content of whole rice
kernel is variable, ranging
between 7-9 percent. It has high levels of aspartic acid,
glutamic acid but low levels of essential amino
acid. Lysine and other amino acids such as isoleusin threonie, tryptophan, methionine and
cystin (Enwere 1998). Rice is unique in richness of -alkali- soluble protein or
glutelin about 70%) where
as the Other cereals are rich in alcohol-soluble protein or prolamin (rice has
about 3 percent prolamin in its gross protein content). The other components of
rice protein include 4-9 percent water soluble proteins or albumins and about
10 percent salt soluble protein globulin. Rice protein are rich in argrinine and contain
trytophan and histidin but are poor in lysined and threomine USA Rice Federation (2002).
Carbohydrates
More than
90 percent of
the energy in
rice comes from carbohydrates.
Rice contains both simple and complex carbohydrates. Simple carbohydrate or sugar includes
glucose, frugse, lacose and suerose. Complex carbohydrate in rice are starch and fibres. About 85 percent of the rice grain weight is
starch. Amylose is the linear fraction of the starch and is negatively co-related with
cohesiveness, tenderness, colour
and gloss of cooked rice USA Rice Federation (2002). Normal rice starch contain about 21-33% amylase
and 64-79 percent amylopectin while some waxy varieties contain 0.2 percent amylase (Enwere 1998).
Food material
may be, it will not be accepted by the consumer
unless it satisfied specific culinary characteristics. Thus the grains of cooked Rice should be non-sticky as well separated qualities that can be judge by
swelling number water uptake and amylase
content
(pushpamma and
Uma Reddy 1979). Cooking improves their digestibility, promotes palatability as well
as making the rice soft to eat. Rice starch
has to be gelatinize during cooking or else rice is too firm to be eaten comfortable U S A Rice
Federation,( 2002).Heat also help to
sterilize the food by killing harmful bacteria and other micro organisms and it
increase the availability of nutrient.
These nutrient
may be lost during cooking in two ways, first
by degradation, which can occur by destruction or by other
chemical changes such as oxidation or
secondly by leaching into the
cooking medium. Vitamins are susceptible
to both losses while minerals are affected
only by leaching. Rice varieties with high protein tend to have worse flavor, and less
tender, less cohesive when cooked in
some amount of water and longer
cooking times are needed because of water
absorption USA Rice Federation ( 2002). Since consumers choice of rice
varieties are largely based on grain and
cooking quality, the high rate of influx
of hybrid varieties and other new rice
varieties to local farmers in the three
zones of Ebonyi state who abandon their hitherto cherished
indigenous varieties without
critical comparison is
unacceptable.