A study on rheological characteristics of roller milled fenugreek fractions

Fenugreek seeds were fractionated by roller milling
to get various fractions. The roller milled fractions and whole
fenugreek flour (WFF) were evaluated for the flow behavior
and time-dependent flow properties using a rotational viscometer
at the temperatures of 10–60 0C. The samples subjected to
a programmed shear rate increase linearly from 0 to 300 s−1 in
3 min and successive decrease linearly shear rate from 300 s−1
to 0 in 3 min. The roller milled fractions and WFF paste
exhibited non-Newtonian pseudoplastic behavior. Difference
in hysteresis loop area was observed among the roller milled
fractions and WFF, being more noticeable at lower temperatures.
Power law and Cassonmodels were used to predict flow
properties of samples. The power law model described well
the flow behavior of the roller milled fractions and WFF at
temperatures tested. Except flour (FL) fraction, consistency
coefficient, m, increased with the temperature
both in the forward and backward measurements. The
roller milled fractions and WFF exhibited rheopectic
behavior that increased viscosity with increasing the
shear speed and the temperature. For all the sample tested,
initial shear stress increased with increase in shear rate and
temperature.