Based on this study, the following conclusions are drawn: (1)
Microwave blanching increases samples dielectric loss factors,
electrical conductivity, while it decreases dielectric constants. (2)
MWB stem lettuce cubes frozen by a quick cooling rate and short
freezing time (1 h) display higher values of e0 and e00 than those obtained
by a long freezing time (4 h). (3) For the samples blanched
by microwave heating total MFD time required in a 70 mm diameter
circular conduit drying chamber was 270 min, less than
360 min in the same conduit diameter for the samples blanched
by boiling water. However, MFD lettuce samples blanched with
MWB retained almost the same quality as those of FD methods.
These results show that microwave blanching may improve MFD
process when applied to plant materials before drying.