Shape. Cooking zones. Stir frying. And why the chef and food can withstand the wok’s high heat.
1-Minute NomNom
One of the great pleasures of food stir fried in a wok is the wok hei. Wok hei is a Cantonese phrase that describes the unique fragrance of food produced at extremely high heat in a wok.
The wok can withstand this high heat because of a combination of metals, materials and polymers (read all about it in the 1-Minute NomNom “Hei, wok’s up?“).
But what about the chef and the food? How do they withstand it?
Look at that runaway pea!
The chef can withstand the high heat – even though he is standing so close to the gas flame – by taking advantage of the shape of the wok. The wok has a convex shape (if you start outside, from the bottom), with its sides sloping upwards.
The convex shapes forces the hot air from the flame to flow quickly up the sides of the wok, carrying heat, steam and smoke away from the chef. At the same time, the chef can tilt the wok at a slight angle so that it shields him from the fire. Where he is standing thus becomes a mini-zone of cool, at least compared to the temperature of the gas flame.
What about the food? That the high heat rushes past the sides of the wok gives you an idea how the food withstands the high heat. A lot of the heat ends up being lost to the environment, and does not heat up the food.
At the same time, the chef is likely to be flicking the wok and tossing the food continuously while he is stir frying (see video above). This creates three zones of cooking that varies the temperature that the food is cooked at (according to the Modernist Cuisine).
The first zone is the conduction zone, where the food is in direct contact with the wok. The conduction zone is very hot – remember it is sitting right on top of the gas flame – and cooks the food very quickly.
The second zone is the convection zone. This is the air above the wok, where the temperature difference between the air and the wok creates convection currents. The temperature here is cooler than in the wok and so this zone will cook the food less quickly.
The third zone is between the conduction and convection zones. It is the condensation zone. In this zone, the steam rising from the wok will condense on any parts of the food that is cooler than it. When it does, the latent heat of this change from the steam to liquid phases will cook the food too.
And that’s how the wok, the chef, and the food withstand the high temperatures to give us delicious dishes!
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