Before first use
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.
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, defrosting 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;
•Defrosting, 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 ...
9
