Pando PHB-961, Руководство пользователя

Страница: 125 / 324

5
Microwave Functions
THE ADVANTAGES OF MICROWAVES
In conventional ovens, heat radiated by
electrical elements or gas burners slowly
penetrates the food from outside to inside.
On account of this there is a major amount of
energy is wasted heating the air, the oven
components and the food containers.
In a microwave oven, heat is generated by
the food itself and the heat travels from
inside to outside. No heat is lost to the air,
the walls of the oven cavity or the dishes and
containers (if these are suitable for use in
microwave oven), in other words, only the
food is heated.
Microwave ovens have the following
advantages:
1. Shorter cooking times; in general these are
up to 3/4 less than the time required for
conventional cooking.
2. Ultra-fast food defrosting, thus reducing the
danger of bacterial development.
3. Energy savings.
4. Conservation of the nutritional value of
foods due to the shorter cooking times.
5. Easy to clean.
How a microwave oven works
In a microwave oven there is a high tension
valve called a magnetron which converts
electrical energy into microwave energy.
These electromagnetic waves are channelled
to the interior of the oven through a wave
guide and distributed by a metallic spreader
or through a turntable.
Inside the oven the microwaves propagate in
all directions and are reflected by the metal
walls, uniformly penetrating the food.
Why food heats up
Most foods contain water and water
molecules
vibrate when subjected to
microwaves.
The friction between molecules produces
heat which raises the temperature of the
food, de-freezing it, cooking it or keeping it
hot.
Since the heat arises inside the food:
•
This can be cooked with little or no
liquid or fats/oils;
•
De-freezing, heating or cooking in a
microwave oven is quicker than in a
conventional oven;
•
The vitamins, minerals and nutritional
substances in the food are conserved;
•
The natural colour and aroma of the
food are unchanged.
Microwaves pass through china, glass,
cardboard or plastic but do not go through
metal. For this reason, metal containers or
ones with metal parts must not be used in a
microwave oven.
Microwaves are reflected by metal...
... but go through glass and china...
... and are absorbed by foods.