Induction cooking technology
The technology behind induction cooking has been around for a while; the first patents were issued over a hundred years ago.
But the early designs were really too cumbersome and expensive to be of much practical use to the caterer, or indeed to the cook at home. And in those days energy, both gas and electric was comparatively cheap.
With modern design, improved technology and rocketing energy prices the game has changed. Contemporary induction hobs are less expensive in real terms than ever before; they are sleek and stylish and much faster than conventional hobs; they are also much more energy efficient.
Traditional cooking appliances, whether gas or conventional electric, simply can’t offer the same benefits.
This article is intended to offer a bit of background to induction cooking, how it works, why it could be good for your business and a brief look at the wide range of induction cooking models that are available in today’s market.
Also, it’s only fair to discuss the drawbacks of induction hobs. There aren’t many, and they’re not major, but it’s only reasonable to point them out.
Cooking on Gas?
Before the arrival on the catering scene of induction hobs, most chefs had a definite preference for gas cooking appliances because of one simple, very good reason; the ability to instantly raise or lower cooking temperatures with great precision. It simply couldn’t be done with electric hotplates because by their nature they take a while to heat up and cool down. Chefs just didn’t have the same finger-tip, immediate control of the dishes they were preparing. No contest.
With induction cooking technology all this has changed.
Not only do induction hobs have the same instantaneous, accurate adjustment of temperature as gas burners, but they use much less energy. There is no wasted heat, or very little, which means substantially cutting running costs.
Added to this is the fact that the stove top itself actually remains cool to the touch, even when full on. Just think: no more burned hands, no more baked on and burnt spillages (they are simply wiped off). No more danger from naked flames. On top of this, the kitchen itself becomes a cooler, pleasanter place to work in. You’d almost think this was some kind of magic.
There are other benefits, which we can look at later, but they’re the main ones.
How does it work?
So, what is induction cooking – and how does it work?
We need to go into a little bit of science, just to make sense of it. But don’t worry, it’s not rocket science!
Induction is the process of heating an electrically conducting object – in our case a pot or pan made from a ferrous material like stainless steel or cast iron – by passing a high frequency electric current through an electromagnet in the “element” and creating eddy currents in the pan itself.
The passage of these oscillating currents through the conductor (the pot or pan) releases heat. The heat thus “induced” is rapidly transferred to the food or liquid within by conduction. That, in a nutshell, is induction cooking.
The heat is generated in the pan itself and not on the hob surface.
In conventional electric cooking of course, the hotplate is heated first and then the pan. This is the reason that heat-up times in induction cooking are so much faster. And it’s also the reason why there’s so little wasted heat: energy is supplied directly to the cooking vessel by the magnetic field. This powerful field is active only in the close area around the cooking zone, and 2 or 3 centimetres above it.
In induction cooking, a whopping 85-90% of energy used is transferred to the actual cooking process. With gas and conventional electric cooking the energy is first converted to heat and only then directed to the vessel.
A solid electric hotplate is typically only 55% efficient; with gas it’s even worse, and usually is in the range 45-50% efficient.
The heat wasted in conventional cookery goes to heating up the kitchen – and the chefs and everyone else who happen to be working there. You get a lot of hot air.
An interesting experiment is to heat a pan of water on an induction hob. The water comes rapidly to the boil yet an ice cube placed alongside it – actually on the hob - remains intact: it does not melt!
You can also try placing a sheet of newspaper, or even a twenty pound note if you’re brave enough, between the hob and the cooking vessel. The paper will not be damaged; it may get slightly warm but it will not get singed.
The surface of the hob is warmed only by the pan, not by the electric element or the gas burner. The fact is, if there is no ferrous metal in the area of the hob, where the magnetic field is generated, then it doesn’t even switch on. As soon as a cooking vessel is removed from the hob, then the generation of heat (and energy consumption) ceases.
We should now have a look at the objections raised against induction cooking.
They aren’t objections at all really, but one fact is this: induction only works with cooking vessels made from ferrous, or magnetic, material; in practice this means cast iron or stainless steel. Also they need to be flat bottomed.
So if your pots and pans are mostly aluminium, copper or glass and you’d like to upgrade to induction technology in your commercial kitchen, you’ll have to upgrade your cooking equipment too. This is unlikely to be an issue though, especially if your existing kitchen gear is relatively inexpensive – or on its last legs anyway.
Interface discs are now available which allow the use of non-ferrous cookware; they are simply placed on the induction hob and the pyrex or aluminium pan sits on that rather than the hob itself.
Interface discs do have a place but the problem is they nullify the benefits of induction cooking. They in effect revert the hob back to a conventional cooker.
Having said all that, most restaurant and hotel kitchens use, and most chefs prefer, stainless steel anyway. Enamelled stainless steel works perfectly well on induction hobs.
Also it may be the case that you’re looking for additional or back-up cooking capacity in a busy kitchen, which is perhaps mostly gas, and you’d like to consider an induction hob for supplementary cooking; to test the water, as it were.
This brings us on to the next point, that of initial cost. The fact is that induction hobs are dearer than gas or conventional electric cookers. This is inescapable: the capital outlay is higher.
This initial outlay, though, is recoverable in reduced energy use and costs. Don’t forget induction hobs typically give 90% energy efficiency, massively more than gas or conventional electric - and they are much faster. An induction hob will pay for itself time and time again.
The old adage “you get what you pay for” holds true: an induction hob provides other benefits too.
With induction cooking there are no naked flames or hot radiant rings, which makes for a much safer kitchen.
It also means the requirement for expensive ventilation is much reduced and a more comfortable working environment for everyone is achieved.
The smooth and flat surface of an induction hob remains cool - it is easy to wipe clean of any spillages; induction cooking is perfect for good hygiene.
So, what’s available?
Today there is a wide variety of induction cooking appliances available, ranging from portable table top units to heavy duty hobs for island suites in the biggest and busiest of kitchens.
There are a number of manufacturers in the UK alone and it’s an extremely competitive market.
Table top induction hobs are portable, plug-in and fairly light duty. They are perfect for front of house use in hotels and restaurants for breakfast or bistro service. And because there is no naked flame or excessive heat they’re great for at-table service too.
Table top induction hobs are available as single, twin or four zone models with total power ratings up to around 6kW.
The larger heavier duty induction hobs have power ratings up to 14kW and more. These obviously need to be hardwired. It’s worth remembering that an induction zone of say, 3.5kW delivers the equivalent cooking power as a gas hob of 6.3kW, or 21500BTU/hour, which is quite extraordinary.
If you are thinking of replacing an old gas or electric model, it’s worth bearing in mind that - because of the faster cooking speed and energy efficiency of induction cooking - it may be possible to replace a 6 burner gas hob with a 4 zone induction hob. The important thing is to get good advice; reputable manufacturers and their agents will be happy to provide this.
Also, some manufacturers include induction hobs as part of a comprehensive range of all types of cooking equipment – ovens, grills, bain marie, hot cupboards etc – so that a neat, modular and space-saving design can be achieved in any commercial kitchen.