2.6. Determination of the morphological properties of the starches
Starch suspensions were frozen at 20 C before being transferred
to a freeze dryer (Dena Vacuum, Esfahan, Iran). Then about
0.1 g of the freeze-dried sample was fixed on an aluminum stub
using double sided adhesive tape and sputter coated with gold to
avoid charging effects under the electron beam. Then the samples
were observed using a scanning electron microscope (Model Leica
Cambridge, UK) at 20 kV and a working distance of 7.5–9.5 mm.