The pasting characteristics of rice flour with different particle
sizes are shown in Table 2. Halick and Kelly (1959) noted that
particle size greatly influenced the pasting characteristics of rice
flour. The initial pasting temperature of HP-80 was 70.40 C and
increased as the particle size decreased. Although peak, trough and
breakdown viscosities differed significantly with particle sizes
(p < 0.05), significant trends were not found. However, final and
setback viscosities were significantly different and increased as the
particle size decreased. The final viscosity of rice flour pasteincreased due to the formed a viscous paste or gel between starch
molecules during cooling. Setback viscosity was calculated by the
difference between final viscosity and trough viscosity. Complete
gelatinized starch granules in rice flour paste not only had
increased viscosity due to the leached-out linear molecules but also
due to the lost crystallinity. The trough viscosity exhibited the
lowest viscosity when starch granules were disrupted during
heating. Therefore, setback viscosity showed a degree of starch
gelation after gelatinization of starch granules in rice flour. Final
and setback viscosities were very important factors to form a
network structure in rice paste without gluten. High WBC, SP, peak
and setback viscosities of rice flour may be considered as the
important properties of starch in rice flour when it replaces the
function of gluten in wheat flour.