(4) reviewed the application of microwave heating in
food processing with reference to the advantages and limitations
for a range of food processing operations.
Microwave penetration depths within a product are determined
by the electrical and physical properties, heating patterns,
microbial inactivation, and safety (5) and can vary significantly
with chemical composition, product temperature,
and the frequency at which the microwave operates. Industrial
microwave systems are available in both batch and continuous
design configurations and use magnetrons that develop either
915 or 2450 MHz (6). Lassen and Ovesen (7) reviewed the effects
of microwave heating on the nutritional constituents of
foods and concluded it does not change the nutrient content of
food to any greater extent than conventional cooking.
The chemical constituents of oils that degrade during microwave
heating do so at rates that vary with heating temperature
and time, as with other domestic processing methods
(e.g., frying, steaming, and roasting). Suitable quality parameters
therefore can be used as time–temperature integrators of
quality deterioration of oils during microwave heating. Monitoring
of many of these parameters makes extensive use of
chemicals. Also, the methods for measuring such components
can be relatively complex and time-consuming, which can be
a major drawback in industrial applications. Instrumental
methods involving simpler and faster techniques for determining
changes in oil are desired.