Abstract SCHIRACK, ANDRIANA VAIS. The Effect of Microwave ...

oils, both ε' and ε" are low and relatively independent of frequency and temperature
(Ryynanen, 1995).
The dielectric properties of shelled and unshelled peanuts have been
measured in bulk samples (Trabelsi and Nelson, 2004). Shelled peanuts have
much higher densities than unshelled peanuts, and the corresponding difference in
dielectric properties relates to the amount of water interacting with the electric field,
as well as proportions of air and dry matter in the peanuts. Trabelsi and Nelson
(2004) also found that in peanuts, the dielectric constant and dielectric loss both
increase with increasing moisture content of the peanuts, while as microwave
frequency increases, the dielectric loss increases but there is little change in the
dielectric constant. A range of dielectric properties at frequencies between 6 and 18
GHz was tabulated (Trabelsi and Nelson, 2004). Likewise, in a study by Boldor et
al. (2004), the dielectric properties of peanut pods and kernels were reported at a
range of temperatures (23-50 °C) and moisture contents (18-39%).
Microwave Blanching of Peanuts
The advantages of using microwaves for blanching include reduced
processing times, increases in shelf stability, and increase in nutrient retention. In a
study using a series of individual trays of peanuts passing through a microwave
applicator, Rausch et al. (2005) examined the potential use of microwaves for
peanut blanching. Reducing the moisture content of the peanuts to 6% using
microwave blanching required 6 minutes compared to 60 minutes using traditional
forced heated air (Rausch et al., 2005). Later refinement of the microwave
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