3.5. Textural properties
Textural properties of starch paste or gel are affected by different
factors including interactions between dispersed and continuous phases, properties of the amylose matrix and volume fraction and
amylose content (Mua & Jackson, 1997). Determination of the textural
properties of samples (Table 3) showed that with increasing
the concentrations of acetic acid, consistency and cohesiveness of
both samples reduced significantly. Similar results were reported
for PG maize and wheat starches as affected by L-ascorbic acid
and native wheat starch as affected by some organic acids including
acetic acid (Majzoobi et al., 2014a, 2014b, 2015). These changes
may be related to the hydrolysis of amylose and amylopectin chains
in the presence of acetic acid resulting in smaller chain lengths of
these molecules. Comparing the samples, PGCS showed higher
reduction in consistency (26.01% vs. 20.05%) and cohesiveness
(46.62% vs. 28.86%) than PGWS. Differences in the molecular structure
and size of these two samples, lower pH of PGCS which may
cause smaller starch molecules as well as higher amount of nonstarch
components in the PGCS which can hinder starch network
development can result in lower consistency and cohesiveness of
this sample.