observed that soy bread had a
lower amylopectin recrystallization with respect to wheat bread
samples when taking into account the lower amylopectin content
in the soy bread. Similarly, in this study, the formulations studied
contained nearly the identical amylopectin contents, yet the rate
and extent of amylopectin crystallization differed. Zeleznak and
Hoseney (1987) reported that starch crystallinity is controlled by
the water present during retrogradation, with maximum crystal
formation at moisture contents of 40–50%. Moisture contents of
the soy bread samples were in this range and it is possible that
the high affinity of soy components for water (higher water holding
capacity) resulted in less water available for the starch component
to recrystallize. In this respect the addition of soy soluble fibre
and soy protein isolate samples may have increased the water
holding capacities and decreased retrogradation to some extent
with respect to the control soy bread, whereas insoluble fibre addition
had an opposing effect. According to Ryan et al. (2002), hydrated
soy fractions in bread interacted strongly with starch,
interfering with the ability of the soy protein to form complexes
with the gluten fraction. This finding suggests that the soy protein/
starch interactions precluded starch/starch interactions hindering
amylopectin recrystallization during storage.