2.3. Drying equipment and procedures
The mushroom slices were subjected to freeze drying (FD) or
freeze drying combined with microwave vacuum drying (FMVD).
Briefly, the samples were frozen at 30 ± 2 C, and FD was carried
out in a lab-scale freeze dryer (Labconco Equipment Co., Kansas
City, MO) at 40 C for 8 h with chamber pressure of 100 Pa and condenser
temperature of 83 ± 1 C (the moisture content of the
sample was 4.19 ± 0.56% (w.b)). The FMVD process was performed
under optimised conditions. Samples were firstly dried by FD for
5 h (the moisture content of the samples was 38.70 ± 2.06%), and
then further processed by microwave vacuum drying (MVD),
which started at 60 W/g under 90 kPa, and remained at this value
for 9 min (0.15 h) using a WZD1S microwave vacuum dryer (Sanle
Electronic Information Industry Group Co., Ltd, Nanjing, China)
(Pei, Yang et al., 2013).