21
Microwaving principles
Microwave energy has been used in this
country to cook and reheat food since early
experiments with RADAR in World War II.
Microwaves are present in the atmosphere all
the time, both naturally and from manmade
sources. Manmade sources include radar,
radio, television, telecommunication links and
mobile phones.
Oven cavity
Base of
the oven
Stirrer motor Waveguide
Microwave
stirrer
Magnetron
In a microwave oven, electricity is converted
into microwaves by the
MAGNETRON
. For
bottom feeding, please refer to page 32.
REFLECTION
The microwaves bounce off the metal walls
and the metal door screen.
TRANSMISSION
Then they pass through the cooking containers
to be absorbed by the water molecules in the
food, all foods contain water to a more or lesser
extent.
Important notes
The dish used to cook or reheat the food
will get warm during cooking, as the heat
conducts from the food. Even in
microwaving, oven gloves are required!
MICROWAVES CAN NOT PASS THROUGH
METAL AND THEREFORE METAL
COOKING UTENSILS CAN NEVER BE
USED IN A MICROWAVE, FOR COOKING
ON MICROWAVE ONLY.
How microwaves cook food
The microwaves cause the water molecules
to vibrate which causes
FRICTION
, i.e.
HEAT
. This heat then cooks the food.
Microwaves are also attracted to fat and
sugar particles, and foods high in these will
cook more quickly. Microwaves can only
penetrate to a depth of 1½-2 inches (4-5 cm)
and as heat spreads through the food by
conduction, just as in a traditional oven, the
food cooks from the outside inwards.
Foods not suitable for cooking by
microwave only
Yorkshire pudding and souffl es. This is
because these foods rely on dry external
heat to cook correctly, do not attempt to cook
by microwave.
Foods that require deep fat frying cannot be
cooked either.
Standing time
When a microwave oven is switched off, the
food will continue to cook by conduction –
NOT BY MICROWAVE ENERGY. Hence
STANDING TIME is very important in
microwaving, particularly for dense foods i.e.
meat, cakes and reheated meals (refer to
page 23).
Boiled eggs
Do not boil eggs in your microwave. Raw
eggs boiled in their shells can explode and
cause serious injury.
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