By: Vladislav Kamikovski
Senior Associate – Toronto
Induction technology has been appreciated by consumers for cooking in Europe and Japan since the 1980s. It seems, though, that the North American foodservice industry is still quite timid about embracing induction cooking as one of the mainstream technologies for cooking. However, with increasing interest in reducing the world’s carbon footprint, and the decrease of carbon fuels such as natural gas and propane, induction cooking will inevitably become more important and widely used.
How does induction cooking work?
The principle of induction cooking has an analogy to a simple line transformer used to transform alternate current from one voltage (primary side) to another voltage (secondary side). A simple line transformer has two wire coils: the primary and the secondary coil, both wrapped around ferritic core and separated one from another. Thus, when there is alternate current – normally at 60 Hz (cycles per second) in North America – running through the primary coil of our transformer, it will form an ever-changing magnetic field affecting free electrons in the secondary coil, and ultimately create or induce current in the secondary coil.
An induction cooking hob contains only a ‘primary’ coil powered by an induction inverter or generator. The inverter is an electronic device providing electrical current at a much higher frequency – the normal operating frequency of an induction inverter is between 20,000 and 50,000 Hz. A cooking vessel, which is just sitting atop of vitroceramic glass separating it from the hob’s coil, becomes the secondary side.
What types of cooking vessels may be used?
The cooking vessel must be made from ferromagnetic material or have a layer of ferromagnetic material in its bottom. As the frequency of alternate current in the coil of the induction hob is at 20 – 50 kHz, its magnetic field will affect the ferromagnetic vessel bottom and push its electrons into a mayhem, creating eddy currents, which results in the heat creation.
One more issue is important for creating heat in induction cooking, and that is the thickness of metallic material in which these eddy currents are formed. For ferromagnetic materials (cast iron, some stainless steel, enameled steel, black steel, etc.), this thickness – ‘skin effect’ as it is called – is about 0.1 mm (0.004 inch) at high frequencies. Such thin skin effect in ferromagnetic materials has high electrical resistance, which helps with the creation of heat. Skin effect in copper or aluminum is much higher – about 5.5 times higher in aluminum – with less electrical resistance – and so it renders these metals unsuitable for cooking with induction.
The use of induction technology for commercial cooking has many advantages.
- The efficiency is much higher when compared to other energy sources such as gas, standard heating, halogen or radiant heating elements. Why? This is because the heat is created directly in the cooking vessel.
- Ventilation requirements are lower since induction hobs create less heat to the environment, thereby creating a more pleasant atmosphere for staff working around induction appliances.
- There is very little or no heat inertia when an operator changes the level of heat on an induction hob control – much like cooking with gas.
- Induction hobs are designed so that when a cooking vessel is removed from a hob, the inverters power down and stop wasting energy.
- Power levels on a hob are adjusted electronically, and the adjustments are normally quite precise. This is important when a low level of heat is needed or for proper simmering.
- The cooking surfaces are normally not as hot as when other methods are used. The heat affecting the cooking surface comes only from the cooking vessel via conduction. This makes cleaning of the appliance easier and it is safer for the operator.
There are disadvantages to induction cooking as well.
- Quality induction cooking appliances are still pricey.
- Natural gas and electricity costs allow efficient open gas burners to operate at a cost that is 10% cheaper than induction cooking appliances.
- As mentioned, not all pot and pans are suitable for induction cooking.
- Inverter electronic components create heat, and proper cooling of electronic parts must be taken into the account when designing and/or installing the hobs.
- Cooking vessels tend to make low humming or clicking sounds when exposed to a hob’s magnetic field.
- Operators with heart pacemakers should be cautious when cook with induction.
It is important to think about the pros and cons of commercial induction cooking technology and its application for your individual foodservice needs. One thing is certain, however. It is time for induction cooking to take its place as a viable option in the North American foodservice arena.