Microwaves

History of Microwaves• In 1945, Dr. Perry Spencer, a scientist,

was working in a lab when he felt some heat on his hand. The heat was coming from microwaves. These were being emitted from a nearby vacuum tube. Dr. Spencer was curious and place a chocolate bar near the tube. Within seconds, the chocolate melted. That sticky mess was the beginning of a brilliant idea – the microwave!

Diagram of a Microwave

How Does a Microwave Work?

• The microwave oven generates electromagnetic waves (called microwaves) which makes water move. This motion leads to friction, and friction leads to heating.

motion friction heating

How Does a Microwave Work?

• This heat starts on the outside of the food and moves in.

• The denser the food the longer it will take to cook.– Water will heat faster than a burrito, because

a burrito is more dense than water.

Microwaves

• Microwaves are attracted to foods that are high in:

water

fat

sugar

Microwave-able Containers

• Paper

• Plastic

• Glass

• Microwaveable Dishes

Non-Microwave-able Containers

• Metal

• Dishes with gold or silver on it.

Acceptable coverings for microwave dishes:

• Paper towel – to absorb moisture, spatters, and spills.

• Wax paper – holds in some of the moisture

• Plastic wrap – hold in moisture

Techniques for Microwaving

• Stirring: To pull heated part of the food to the center

• Turning over: To microwave all sides• Rotating: Makes cooking even• Pricking: To keep foods from exploding• Standing Time: To allow foods to complete

its cooking by placing on the counter.

Cooking Time

• These will increase the cooking time and standing time.– The volume of the food

• Example: Small potatoes versus large potatoes

– The quantity or number of food– Round containers will cook more evenly than

square containers.

Microwave Safety

• To prevent burning yourself from microwave cooking, remember:– Foods can create hot containers– Items can explode (eggs, potatoes). Pierce

them with a fork.– Lifting the cover or plastic from the food can

cause a burn.– Hot steam escaping can cause a burn

What foods should not be microwaved?