2.6. Rheological characterisation
The flow curve and viscoelastic property of whole wheat flour
(WWF) with the addition of 10% of unprocessed hull powder
(SBH-C) or hull dietary fibre powder (SBH-T) were measured by
Physica MCR 301 Rheometer (Anton Paar, Ashland, VA, USA). The
method of yield fluid with logarithmic ramp stepwise was selected
from a standard template in the RheoManager software. The flow
curve was evaluated on a stress-controlled rheometer equipped
with 50 mm smooth parallel plate geometry (50 mm diameter,
2 mmgap). Dough was mixed at 30 C until well developed. A sample
of dough with 50% moisture content was immediately removed
from the bowl and placed between the plates of the rheometer.
Excess dough was carefully trimmed. Sample was rested 10 min
after loading before testing. Viscosities were measured for shear
rate increasing from 0.01 to 250 s1 at 25 C. In a dynamic test,
the method of amplitude sweep under oscillation category with
LVE-range and structural strength was chosen from a standard
template. The dough with 50% moisture content was placed
between two parallel plates, and the gap between two plates was
set to 2.0 mm. Strain ranged from 0.01% to 100%. Angular frequency
was set at 10 rad/s. The storage modulus (G0), loss modulus
(G00), and damping factor (tan d) were recorded.
2.7. Statistical analysis
All measurements were performed at least three times with
data expressed as means ± standard deviations, and reported on a
dry matter basis. One-way analysis of variance (ANOVA) was carried
out to assess for any significant differences between the
means. Differences between means at the 5% (p < 0.05) level were
considered significant.
3. Results and discussion
3.1. Physicochemical properties analysis of soybean hull fibre
3.1.1. Colour
The colour difference in unprocessed and processed soybean
hull powders was visually shown in Fig. 1(b). Table 1 displayed
the parameters (L⁄, a⁄ and b⁄) of HunterLab colour in control and
treatment. The L⁄ reading is an indicator of brightness of the