Cooking in a microwave oven
Standard power ratings
Almost all microwave ovens sold after September 1990 have been tested to standard specifications for power output. Check it has been tested to standards laid down by the International Electronic Technical Commission. Methods of rating older ovens vary. If in doubt, contact the manufacturer and ask for the new rating for your model.
Adjusting cooking times for different power ratings
Cooking times given in recipes and on packs of prepared food usually assume a 600W or 650W oven. If your microwave has a higher or lower rating you will need to shorten or lengthen the time accordingly. There’s no foolproof way of converting, as time also depends on oven capacity, but as a rough guide, lengthen the time by one-quarter for ovens of 500W or less, and reduce it by one-tenth for ovens of over 700W.
Find the hot spots
Here’s a simple test to reveal variations in oven temperature. Cover the floor of the oven with slices of white bread with the crusts removed. Set the oven to High (100 per cent power) and watch through the door to see where the bread browns fastest.
What’s safe to use?
Non-metallic containers such as glass, china, earthenware, some plastics and polystyrene are best – as well as anything manufactured for microwave use or labelled ‘microwave-safe’. Avoid metal containers. The microwaves will bounce off them, creating a flashing effect known as ‘arcing’ which can damage the oven.
Don’t cook foods rich in fat or sugar in plastic. The high temperatures they reach could melt the container.
Wood and wicker
Microwaving dries out the natural oils in wood and wicker, and wicker has been known to catch alight, so avoid using them in a microwave.
Not sure if a dish is suitable?
Before you risk a favourite dish or a special piece of china, try this simple test: place the empty container in the oven with a small glass of water standing in the centre.
Heat for a minute on High (100 per cent power). If the water heats up but the dish stays cold, you can safely use it in your oven. If the container is hot and the water cool, don’t use it.
Use boiling, roasting or special microwave cooking bags to keep food juicy and your oven clean. Always pierce the top of the bag first, to allow steam to escape.
Bigger is better
Choose a slightly larger container for microwave cooking than you would otherwise use. This gives liquids room to boil without spilling, and makes stirring or turning easier.
Round or square?
Round dishes are much better for microwaving than square or rectangular dishes, which have a tendency to overcook food in the corners.
Choose a shallow, open dish for faster cooking. It exposes a greater surface area of food to the microwaves.