Methods of Cooking Food
Cooking is the application of heat to food to produce a meal for consumption. Although there are many means to generate heat to do this, the three more common methods of hob based heating used in our homes today are:
1) Chemical – This involves burning a variety of combustible materials such as coal, charcoal, wood or gas. The materials are ignited and the flame that is generated produces heat.
This heat is then transferred to the cooking vessel via the surrounding air.
2) Electrical – Running an electrical current through a resistance element also generates heat. Basic examples of this include electrical cooker coils and toasters.
Even the basic filament light bulb works using this process. Again, when heat is generated by the ring for cooking the heat is transferred to the cooking vessel or directly to the food via the excited molecules in the air.
3) Induction Cooking – this process makes use of well established electromagnetic technology that has been known about since the early 1900’s. The method is based on electro- magnetically exciting the tiny molecules within the metal contained in compatible magnetic based cookware itself (i.e. made of stainless steel of iron).
This method is distinct from the aforementioned methods as it turns the cooking vessel itself into the source of the heat. It does not rely on the heat transfer method used in examples 1 and 2.
How Does Induction Cooking Work
The following elements are required to create the induction cooking process.
1) An electrical supply
2) A coil of copper wire mounted beneath a glass ceramic cooktop surface
3) A cooking vessel made of stainless steel or iron – although Panasonic have recently developed new technologies that will overcome this barrier.
The induction heating process can be demonstrated by viewing the image below:
1) The electrical supply is applied to a copper coil which in turns generates a high frequency electromagnetic field. This is shown above as the two amber arcs.
2) The electromagnetic field interacts with the ferrous based (magnetic-material) cooking pot or pan via the ceramic glass cooktop.
3) The glass ceramic cooktop is the surface which separates the copper coils and components from the cooking vessel itself. This material is known to be a poor conductor of heat and so little heat it lost back through the bottom of the cooking vessel. It is such a poor conductor that the cooktop will stay cool to the touch once the vessel is removed from the hob.
4) At a molecular level, eddy currents are generated within the ferrous metal of the magnetic cooking pot. It is this eddy current as well as a process known as that generates the heat in the cooking vessel. Heat is also created by the process of “hysteresis”. The ferrous material generates heat as it resist the rapid changes in magnetization.
5) The heat produced within the cooking vessel material is then transferred to the vessel’s contents as it is in direct contact with the vessel. This process is known as heat conduction.
6) Nothing outside the cooking vessel is affected or heated by the harmless electromagnetic field.
7) As soon as the element is switched off or the vessel is removed from the surface of the ceramic plate the heating process stops.
Check out the following videos for more insight into the induction cooking process.