To demonstrate the effect of glutelin and globulin on the pasting
properties of rice starch, glutelin and globulin were added to starch
at the level of 50 mg/g and 20 mg/g, respectively, followed by
measurement of their pasting properties by RVA. The addition of
both glutelin and globulin to rice starch resulted in significant
changes (P < 0.05) in its pasting behaviour; however, the effects of
the two protein fractions were different and, sometimes, opposite
to each other (Table 1). Adding glutelin to rice starch caused a 5 C
(more than 8%) increase in pasting temperature whereas the
addition of globulin resulted in a small (slightly over 3%), but statistically
significant, decrease in the parameter. The addition of both
glutelin and globulin caused decreases in the viscosities of the
starch paste, but the magnitude of the decreases was substantially
greater with the former. For example, the addition of glutelin
resulted in the peak viscosity to decrease by 35 RVU, compared
with a 16 RVU drop caused by globulin. This experiment was
repeated six more times using proteins extracted from two other
rice cultivars (Langi and Amaroo) and rice grown under different
levels of nitrogen fertilisation and in one case, under the stress of
salinity, and the same data trends were found in every experiment