Description of the functions
31
In a microwave oven there is a high-
frequency tube called a magnetron.
This converts electrical energy into
electromagnetic waves (microwaves).
These microwaves are distributed
evenly throughout the oven interior, and
are reflected off the metal appliance
walls. This enables the microwaves to
reach the food from all sides and heat it
up. Microwave distribution is improved
with the turntable engaged.
In order for microwaves to reach the
food, they must be able to penetrate the
cooking container being used.
Microwaves can pass through
porcelain, glass, cardboard and
plastics, but not metal. Therefore do not
use utensils that are made of metal or
contain metal, for example in the form
of gold or silver trim. The metal reflects
the microwaves and this could lead to
the creation of sparks. The microwaves
cannot be absorbed.
Microwaves pass through a suitable
container and into the food. All food
contains water molecules which, when
subjected to microwave energy, start to
oscillate 2.5 billion times a second. This
vibration creates heat. It first starts
developing around the outside of the
food and then slowly penetrates
towards the centre. The more water a
food contains, the faster it is heated or
cooked.
The heat is produced directly in the
food. This has the following
advantages:
– Food can generally be cooked without
adding liquid or cooking oil, or with just
a little water or oil.
– Cooking, reheating and defrosting in a
microwave oven is quicker than using
conventional methods.
– Nutrients, such as vitamins and
minerals, are generally retained.
– The colour, texture and taste of food
are not impaired.
Microwaves stop being produced as
soon as the cooking process is
interrupted or the appliance door is
opened. When the appliance is in
operation, the closed, sealed door
prevents microwaves escaping from the
appliance.
