31) at 175 °C for 20 min. After baking, the cakes
were removed from the pans, cooled upside down
on a wire rack for 30 min at room temperature
and kept in plastic bags to prevent drying before
being measured for physical properties and sensory
evaluation within 12 h.
Batter quality measurement
Apparent viscosity
The shear stress and apparent viscosity
of the prepared batters were recorded as a function
of a shear rate range between 2.5 and 62.5 s-1
controlled at 25 °C using a rotational viscometer
(DV-III, Brookfield-RVT) with the coaxial
cylinder geometry of the small sample adapter and
the SC4- 29 spindle according to the method of
Ketjarut et al. (2010). Sample temperatures were
kept constant for at least 5 min before starting
measurements. The flow behavior of each batter
formulation was evaluated using a power law
model as shown in Equation 1 by plotting ln (shear
stress) and ln (shear rate) to obtain the consistency
coefficient (K) and flow behavior index (n):
τ = Kγ˙ n (1)
where: τ = shear stress (Pa)
γ˙ = shear rate (s-1)
K = consistency coefficient (Pa.sn)
n = flow behavior index.
The coefficient of determination (R2) was
also calculated. All measurements were carried out
at a controlled temperature (25 ± 2 °C). At least
three replications were completed.
Batter density
The batter was filled into an aluminum
cup immediately after removal from the mixer,
leveled off using a rubber spatula and weighed.
The batter density was calculated as the ratio of
the batter weight (W1) to the distilled water weight
(W2) filled in the same cup (modified from Gomez
et al., 2007). The density of the water was 1
g/cm3.