Starch extracted from cassava roots was also
variable in its structure–function properties, depending
on variety and environmental growth
conditions. The outward appearance of the granules,
irrespective of harvest time and growth conditions,
are identical. Granules are mostly round
and truncated at one end with different size distribution
characterizing each variety (Fig. 2). Starch
granules from the crop with initial water stress
were smaller relative to those from the crop without
initial water stress. This is indicated by a
higher proportion of small starch granules.
Initial water stress not only influenced the
structural properties of starch, but also its functionality,
especially hydration capability. The hydration
and gelatinization properties of the
starches were influenced by variety, initial and
harvest conditions (Table 1). Common to all varieties,
starch extracted in the early development
stage from roots subjected to water stress swelled
less than that of the corresponding starch from
the crop without initial water stress (Table 4). The
ability to swell was also minimal when roots were
harvested during the onset of heavy rainfall; this
is common to all varieties. Water absorption was
effected in a similar way, though the magnitude of
responses to stress was different. Swelling power
of the starch granules obtained from the crop
with initial water stress ranged from a maximum
of 45.1 to 51.7 (for R1 and R5) and a minimum of