Drying causes irreversible changes in the material. Even if the time of rehydration
would be infinite, the material does not absorb as much moisture, as it lost during drying (Witrowa-Rajchert, 2004). However, from the viewpoint of consumption, dried
material should be characterized by the greatest return to initial weight. Fig. 9
indicates that the ratio of return to initial weight is higher for samples dried with US.
The difference between samples dried with US power 100 W and 200 W is about 4 %
in favor of 200 W power.