Microwaving Techniques

A microwave oven cooks food by causing the moisture molecules in food to vibrate, producing friction, which results in heat. The microwaves are reflected off the metal cavity of the oven, ensuring that the food absorbs waves from all directions. Although microwaves can only penetrate about 5 cm (2 in) into the food; the centre of larger pieces of food is cooked by the conduction of the heat produced near the food's surface.

Microwaves can pass through paper, plastic, china and glass, making them all suitable microwave containers. However, you should never use the following items in a microwave:

  • Metal containers
  • Dishes with gold or silver decoration
  • Jagged pieces of tin foil
  • Anything containing glue
  • Pottery (it may have a metallic glaze)
  • Melamine
  • Thin-stemmed glasses
  • Crystal glass

Microwaves are particularly useful for reheating, melting and defrosting food in small quantities. It is less useful for cooking or defrosting food in large quantities, as it often produces food that is frozen or uncooked in one area, whilst overdone in another. To prevent this, you must stop the microwave every so often and allow the food to stand so that heat can be conducted to the centre.

Microwaving is also a useful technique for cooking vegetables that would normally be boiled, such as peas and asparagus. They may also be used as a fast way to cook baked potatoes; however, you should put the potato in the a hot oven for 15-20 minutes after microwaving if you want the potato to have a crispy skin and a 'baked' taste.


1. Melting or softening butter.
2. Cooking baked potatoes.
3. Reheating plated meals and hot drinks.
4. Cooking small pieces of fish.
5. Cooking vegetables in a minimum of water.

Microwaving Tips

  • There is a fixed amount of microwave energy which will be divided between all the items of food, so 2 items will take twice as long to cook as one.
  • Do not place food in the centre of the turntable; place it slightly off-centre so that it travels all around the area of oven's cooking cavity, thus assuring even heating.
  • Cover food with clingfilm (pricked to allow steam to escape). Tinfoil will reflect the waves.
  • The colder the food is, the longer it will take to cook.
  • The more even the shape of the food, the more evenly it will cook.
  • A dense food is more difficult to reheat than one with a light, open texture.