Stability and setback ratio increased as the level of soybean
flour increased. Stability ratio explains the resistance of a
starch paste to viscosity breakdown as shear is applied.
Composite flours showed significantly (P < 0.05) higher stability
ratio (Table 3) than those of wheat flour. The blending
of sweet potato flour, maize starch, soybean flour and xanthan
gum gave the flours a longer paste peak times, and hence
swelled more gradually and not as susceptible to mechanical
damage (Wiesenborn et al., 1996). Setback ratio, which is an indication of starch retrogradation tendency after gelatinization,
was significantly lower (P < 0.05) in composite flour
than those in wheat flour. The value of setback ratio of composite
flour was between the value of setback ratio of sweet
potato flour and maize starch