During the MFD process, samples were withdrawn at 30 min
intervals from the circular conduit drying chamber and weighted
using a digital balance with 0.1 g precision (FA1104 electronic balance,
Shanghai Scale Factory, China). 200 ± 0.5 g frozen samples
were dried for 30 min then taken out for moisture measurement
before being discarded and another batch of frozen samples was
dried for 60 min before moisture measurement. The same procedure
was done until the end of drying process. MFD process was
continued until weight loss variation was below 0.1 g between
consecutive measurements. The dried samples were immediately
heat sealed in polyethylene bags after MFD/FD processes for storage
until further analyses.
All the drying experiments were done in triplicate and the average
value of three measurements of moisture content were used to
plot the drying curves.