3.7. Dielectric behaviour measurements
Dielectric spectra representing dielectric constant (ε′) and dielectric
loss factor (ε″) were plotted as a function of frequency for all the
treatments (Fig. 4). The ε′, which is the ability of a product to store
electromagnetic energy, increased with increasing frequency up to
~10 GHz, then decreased sharply up to 20 GHz. A similar trend of ε′
is usually observed for pure water between 10 and 20 GHz (Gabriel,
Gabriel, Grant, Halstead, & Michael, 1998). The PEF treated samples
had a lower ε′ between 10 to 20 GHz compared to the control and
water bath treated samples. This may be a representative of the greater
drip loss that occurred immediately post PEF treatment. The ε″ for
all treatments decreased from 500 MHz to ~5 GHz and then steadily
increased up to 20 GHz. This trend of the ε″ spectra was the same
for all the treatments and followed a similar trend to that reported