Effect of different drying methods and conditions on the
structure of dried mushrooms was observed under scanning
electron microscope. In air-dried samples (Fig. 13a)
there is very less open structure and pores as compared
to microwave-vacuum dried samples (Fig. 13b and c), indicating
severe tissue shrinkage and collapse during air drying.
The less shrinkage in the microwave-vacuum dried
samples may be due to the shorter drying time, lower drying
temperature and some tissue expansion from internal
water vapour. Again the structure is more porous in samples
dried under more vacuum conditions (Fig. 13c) during
microwave-vacuum drying.