Microwave Basics

Susan Hansen, Extension Educator, Colfax County

PO Box 389, Schuyler, NE 68661

 

A microwave oven is a staple in most homes but many of us remember when microwaves first commonly entered the kitchen in the 1970’s. For many people, it was a new way of cooking.  The use of microwave ovens hasn’t changed much over the years yet it is still important to teach new users how to properly and safely use the appliance.

 

Microwaves were discovered in the mid-1940’s by a scientist in Great Britain.  He was working with a magnetron and the waves produced by the magnetron melted the candy bar in his shirt.  More research led to the development of the microwave oven we use today.

 

How does a microwave work?  The waves pass through china, glass and paper to reach the food.  The water molecules in food vibrate from the microwaves and produce heat.  Essentially, microwaves steam foods.  The waves cook the outside first and then heat is conducted to the interior.  Food does not cook food from the inside out.

 

Do not use metal containers or items containing metals.  Microwaves are an electromagnetic field so when microwaves come in contact with a metal, sparks can occur.  Some paper bags, recycled paper or newsprint may contain small amounts of metal so do not use those items in the microwave oven.  Waxed paper, cooking bags, parchment paper, paper plates and white paper towels are safe to use.

 

Regarding plastic containers, use only those that are marked as safe to use in a microwave.  Margarine tubs or other similar containers are not recommended.  Also remember that microwavable plastic containers do not last forever and will need to be replaced after multiple uses.

 

What about plastic wraps?  There are plenty of urban legends around about the use of plastic wrap in the microwave and the formation of plasticizers.   To be on the safe side, buy polyethylene wraps (commonly found in your grocery store – read the label).

 

Most food can be safely cooked in the microwave.  Anything in a tight skin or shell needs some extra precaution since the water inside will expand and burst through.  For root vegetables such as potatoes, prick the skin or remove a strip of peel to provide an exit for the steam.  Eggs should always have the shell removed and the yolk pierced to allow for the steam to safely release.  When opening a cooking bag or bag of microwaved popcorn, open slowly and away from the face – that steam is hot!

 

Reheating food is the most common use of microwaves.  Food needs to be reheated to 165 degrees F to safely kill bacteria.  Since microwave ovens commonly cook unevenly, use a thermometer to check temperature.  A turntable will help with even cooking as will turning and/or stirring the food halfway through cooking.

 

Some people use the microwave for defrosting.  This works well but remember to continue cooking the food thoroughly after defrosting since defrosting actually starts the cooking process.

 

Food is cooked or reheated much more quickly than conventional methods so plan accordingly.  Warming up bread products take only a few seconds compared to minutes in a regular oven.  A piece of bread warmed up in a microwave too long will gain new life as a crouton or bread crumbs since there is no cure to return it to a soft piece of bread.

 

A common question is whether to warm a baby bottle in the microwave.  The answer is a cautious yes.  Remember that microwaved items may cook unevenly so stir or shake the heated bottle to eliminate hot spots.  Test the heat of the milk or formula on your wrist and fingertips since these are sensitive areas.  If in doubt as to whether the liquid is too hot, take the safe route and wait for it to cool a little bit.  The bottle may feel cool but the liquid may be too hot to drink.