Cooking Appliances Made Simple!

An Insight into Microwave Technology....

The history of microwave ovens dates back to World War II, when it was accidently discovered by Percy Spencer, who worked as an engineer with Raytheon Corporation. Working with a magnetron one day, he found that the candy bar in his pocket had melted due to the intense heat produced by the magnetron. This got him to experiment further, using the magnetron as a source of energy to cook food, which ultimately led to the production of the first commercial microwave oven in 1954.

The domestic microwave oven was first introduced in 1967 by Amana Corporation.  However large cavity sizes and high prices were a deterrent to sales until the 1970's when a number of other companies joined the race and started producing lower priced domestic microwave ovens.

Microwave ovens have since been considered a revolutionary kitchen appliance that can heat, cook and defrost food with incredible speed and efficiency. However their versatility is one of the least understood in kitchen appliances. I believe an insight into microwave technology and its working can help you get the maximum out of your machines. 

It is often said that "microwave cooking is different from conventional cooking".  Let's try and understand why….

In a conventional oven, the oven walls and air inside the cavity heat up, due to heat generated by heating elements located at the top and bottom of the oven cavity. This heat is then transferred to the container holding the food, which in turns conducts it to the surface and eventually to the core of food. This may sometimes result in overcooking the surface while the centre of food might still remain a little cold / under done.


In a microwave oven however, the oven walls and air inside the cavity do not heat up.

Microwaves are in fact short frequency, high wavelength, electromagnetic waves (similar to television or radio waves), generated by an electronic device called a "magnetron". 

  • When a microwave oven is connected to a socket, it converts electric energy to electromagnetic waves by passing them though an electron vacuum tube. 
  • High frequency microwaves thus produced are directed into the oven cavity by a wave guide.
  • The turntable distributes the microwaves evenly throughout the cavity.
  • The oven cavity, (made of metal) reflects the microwaves without absorbing them. These microwaves bounce off and across the metal walls, in a regular pattern, and are distributed evenly thought the oven cavity by a stirrer fan.
  • These waves are absorbed by the food directly, penetrating the container holding it, resulting in the production of heat that cooks food evenly and uniformly, while keeping the oven walls cool to touch.

As you know, food is primarily made up of sugar, fat and water molecules. Microwave energy on entering the food, is absorbed by these molecules making them vibrate at an intense rate, causing friction between them.  The heat thus produced results in cooking the food quickly as compared to other methods of cooking like gas stoves (where the heat from the burner is transferred to the container and then conducted to the food) or incase of conventional ovens (where heat from the elements is transferred to the container and ultimately conducted to the food).  As the agitation of water molecules takes place throughout the food mass simultaneously and uniformly, food is cooked quickly and evenly.

However remember microwaves can effectively penetrate food up to 1.5 inch (4 cms) in thickness. Thus pieces of raw food larger than 3 inches would remain undercooked at the centre (since the centre would be dependent on heat received through conduction from segments nearer to the surface) while the outer surface of food might get overcooked. It is therefore recommended to cut fruits, vegetables, meats etc. into equal sized pieces smaller than 3 inches (in height) to promote uniform cooking while using the "microwave" cooking mode.