decreased breakdown viscosity. Interestingly, it was firstly reported
that potato starch after annealing at 50 C presented a continuously
increasing viscosity during the whole RVA testing (Fig. 3c). The
ethanol-dehydrated potato starches presented a similar pasting
profile as did the corresponding freeze-dried starches (Fig. 3d).
3.6. In vitro enzymatic hydrolysis
The in vitro enzymatic hydrolysis curves of native and annealed
starches are shown in Fig. 4. No significant changes were observed
in in vitro enzymatic digestion between native and annealed wheat
starches at 30 and 40 C. However, annealing at 50 C increased
greatly the in vitro digestion percentage of wheat starch over the
whole period of incubation (Fig. 4a). Annealing did not alter greatly
the susceptibility of yam and potato starches to in vitro enzymatic
digestion, except for freeze-dried potato starch after annealing at
50 C, which showed a lower digestibility (Fig. 4b, c).
4. Discussion
4.1. Effect of annealing on starch structure
Annealing did not alter significantly the granular morphology,
long- and short-range ordered structure of wheat, potato and yam
starches, with the exception of the annealing of wheat starch at