12
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.
Microwaving principles
Reflection
The microwaves bounce off the metal walls and the metal door screen. In a microwave oven,
electricity is converted into microwaves by the MAGNETRON.
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.
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 1
1
⁄
2
-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.
IMPORTANT NOTES
The dish used to cook or reheat the food will get warm during cooking, as the heat conducts
from the food. Even when micro waving, oven gloves are required!
MICROWAVES CANNOT PASS THROUGH METAL AND THERE FORE METAL COOKING
UTEN SILS CAN NEVER BE USED IN A MICROWAVE, FOR COOKING ON MICROWAVE
ONLY.
Foods not suitable for cooking by microwave only
Yorkshire puddings, souffles, double crust pastry pies.
This is because these foods rely on dry external heat to cook correctly, do not attempt to cook
by micro wave.
Foods that require deep fat frying cannot be cooked either.
Boiled eggs
Do not boil eggs in your microwave. Raw eggs boiled in their shells can explode and cause
serious injury.
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 13).
How Microwaves cook food
