Rehydration characteristics
The rehydration curves of microwave-vacuum dried
mushroom samples, both at ambient (30 C) and at 100 C water temperatures, as affected by microwave
power and pressure levels are shown in Figs. 9 and 10.
In all the cases the amount of moisture absorbed increases
with rehydration time, but at a decreasing rate up to saturation
level. The rehydration stabilized in about 10 min
at 100 C and in 3 h at 30 C and the rehydration ratio
was in the range of 2.3–3.4 under various drying conditions.
Rehydration properties were improved by drying
at lower system pressure and higher microwave power
as indicated by higher values of rehydration ratio. Similar
results were reported by Drouzas and Schubert
(1996), Durance and Wang (2002), Pappas, Tsami, and
Marinos-Kouris (1999). The regression model for RR
relating the microwave-vacuum drying process variables
was found as