RF energy provided by electrodes positioned between a product is used to heat
a product that exhibits a variable impedance during the heating process. As the
product's impedance changes during the heating process, RF heating system impedance
can be maintained constant by adjusting the distance between the electrodes, adjusting
the impedance of a variable impedance device connected between the RF power source
and an electrode, or a combination of electrode distance adjustment and impedance
adjustment of the variable impedance device. The system is particularly applicable
to the heating or pasteurization of bulk food products with multiple heating zones.
