2.8. Scanning electron micrographs (SEM)
The morphological changes in bran before and after extraction were studied by a Hitachi S-4800 scanning electron microscope system (Hitachi Corporation, Japan). Samples were dried at 105 ℃ for 24 h, then were fixed on a specimen holder with an aluminium tape and sputter-coated with gold. The images were obtained under vacuum with an acceleration tension of 15 kV.