Cooking and the Leidenfrost effect

I think there needs to be more mentions about cooking and the Leidenfrost effect (see Wikipedia for more details) — it is much too cool not to share if you have not heard about this incredible science phenomenon that occurs in your pans as you heat them up.

Before we start cooking in class, the chef instructors always remind us to make sure that our pans are hot enough and also to look for the “Leidenfrost effect” which is a clue for newbies (like us) to test whether we got enough heat in the pan before we start pan-frying/sauteing/wok-frying/etc.

The Leidenfrost effect (also known as the water-test, mercury ball test, among other names) occurs when the heat of the pan gets hot enough that the water on the pan will bunch up like small balls rolling around.

The method applies for any types of pans – stainless steel, cast iron, teflon-coated or in a wok.hotpan_1 hotpan_2

(Before you add oil to your hot pan, make sure it is dry first.)

The Leidenfrost effect is not really a practical way in a professional kitchen, so other tips on knowing when you get a pan that is hot enough to start cooking are:

  • Look for grey steam, grey steam is good. If you start seeing white steam come off your oil, it is a signal that you will start burning your food.
  • Monitor your pan – don’t turn on the flames, walk away and then come back to pan. This is a very bad habit if you’re doing this.

Also, remember this mind-blowing thought (at least it is to me):

  • The surface of your metal pan is actually porous. When you add enough heat to metal, the metal will expand, which closes up these pores, so when you put your piece of chicken down (with some oil), it will not stick to the pan! However, the chicken will stick to the pan when the pan is not hot enough as it would get “caught” in these pores. Mind-blowing. 🙂

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