Cereal Starches
Starch is the second most abundant biopolymer after cellulose. It is synthesised by plants, stored in organs such as seeds and tubers, and subsequently used as an energy source during germination and growth. Starch is stored in distinct granules, the carbohydrates in these granules comprising two polydisperse polymers, amylose and amylopectin. Both of these polymers are composed of α-D-glucopyranose subunits. Amylose is an essentially linear polymer with the subunits being connected by α-(1→→4)-linkages. Amylopectin is a highly branched polymer in
Rice,morethananyothercerealexhibitsverywideangesofcookingqualityandrheological
properties
that
are
largely
deter-
mined
by
the
swelling,
gelatinization,
pasting,
and
retrogradation
characteristics
of
its
starch
(Juliano
1985).
Being
a
diploid
cereal,
rice
has
numerous
stable
starch
variants
commonly
classified
as
high-,
intermediate-,
and
low-AM
and
waxy
(zero-AM).
Each
of
these
types
normally
includes
varieties
with
low,
intermediate,
and
high
gelatinization
temperatures
(GT).
In
this
study,
six
low-
GT
and
six
high-GT
waxy
rice
starches
with
contrasting
gel
properties
were
used.
In
addition,
swelling
factor
was
measured
using
some
waxy
rice
starches
described
previously
(Morrison
et
al
1984,
Morrison
and
Nasir
Azudin
1987).
