Microwaves And How They Work; Food Characteristics - Panasonic NN-GD37HB Operating Instruction And Cook Book

Microwaves and How They Work

Microwaves are a form of high frequency
electromagnetic waves (app. 12 cm wave length)
similar to those used by a radio. Electricity is
converted into microwave energy by the magnetron
tube. The microwaves travel from the magnetron
tube to the oven cavity where they are reflected,
transmitted or absorbed.
Reflection
Microwaves are reflected by
metal just as a ball is bounced
off a wall. A combination of
stationary (interior walls) and
rotating metal (glass tray or
stirrer fan) helps assure that the
microwaves are well distributed
within the oven cavity produce
even cooking.

Food Characteristics

FOOD CHARACTERISTICS
Food characteristics which affect conventional
cooking are more pronounced with microwave
heating.
Size –– Small portions cook faster than large ones.
Shape –– Uniform
sizes heat
more evenly. To
compensate for
irregular shapes,
place thin pieces
toward the centre
of the dish and
thicker pieces toward the edge of dish.
F0003BW60HP.indd Sec1:24
Transmission
Microwaves pass through some
materials such as paper, glass
and plastic much like sunlight
shining through a window.
Because these substances
do not absorb or reflect the
microwave energy, they are
ideal materials for microwave
oven cooking containers.
Absorption
Microwaves are absorbed by
food. They penetrate to a depth
of about 2-4 cm. Microwave
energy excites the molecules
in the food (especially water,
fat and sugar molecules), and
causes them to vibrate very
quickly.
The vibration causes friction and heat is produced. In
large foods, the heat which is produced by friction is
conducted to the center to finish cooking the food.
Starting Temperatures –– Room temperature foods
take less time to heat up than refrigerator frozen
foods.
Bone and Fat ––
Both affect heating.
Bones may cause
irregular heating.
Large amounts of fat
absorb microwave
energy and meat
next to these areas
may overcook.
Density –– Porous, airy foods take less time to heat
than heavy, compact foods.
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