How do you know if your pan or plancha is hot enough? An easy way to assess the temperature of of cooking instruments without using a thermometer .
By sprinkling a few drops of water on a stove, a griddle, a grill or other cooking instrument, you can easily assess the temperature . If you want to sear food, then it is essential, especially if you want to limit the use of fat.
How? Wet your fingers, sprinkle a few drops of water on the hot surface and observe:
Less than 100 ° C: the drop spreads and evaporates quietly.
Above 100 ° C: the drop boils, you hear it sizzle and it evaporates much faster.
Over 160° C: the drop makes bouncing beads that roll and dance on the hot surface. The evaporation is very slow ...
Why? When your plancha plate or your pan is hot, a small part of a drop of water is immediately converted to steam. And this vapour that is much cooler than the plancha insulates the drop ... When there is no more steam to protect the drop and it is once again in contact with the hot plate, the water vaporises again and leaps and bounces. This layer of insulating steam is very fine (± 0.1 mm.), but sufficient to make the drop look as if it is on an air cushion. This is the Leidenfrost effect, after the German scientist who first explained the phenomenon in 1756.
Why is it interesting in cooking? If the water drop test allows us to assess the temperature of our cooking instruments, it also allows us to better understand why it is important to sear on a hot surface. As all the food we cook contains water, we can deduce that the Leidenfrost effect and its insulating vapour layer is also applicable to a salmon steak or a tournedos. The flesh that is actually in contact with the plancha will lose its water and grill but the released steam will ""insulate"" the food and prevent overcooking.
The right temperature. Seeking to understand what practical applications could be drawn from the Leidenfrost effect, scientists accurately determined that at 200° C a drop of water can keep longer on a hot surface. From there to say that the ideal temperature of your plancha would be 200° C is a leap, but it is tempting. In any case, the theory is interesting. Too hot, and you will burn the plancha cooking oil and animal fats and emit toxic fumes and that is far from the healthy and nutritional cooking that we want!
In closing ... To say that with a hotter plate, cooking is less intense may seem paradoxical. Yet Leidenfrost and protective vapor is easily demonstrated in the kitchen. Just cook a steak at medium heat to find that, despite the absence of a grilled exterior which proves that the surface has not been subjected to high temperatures, our poor steak is typically overcooked and
tough... The phenomenon could also explain why some people manage to walk on hot coals without burning their feet. Quite honestly, a 1,000° C brazier is offputting and I have no interest in doing something idiotic, so I will settle for testing my theory with friends on some tuna steaks!
Enjoy using your planchas...
PB
Sources: Jearl Walker, CNRS, Franck Celestini, BBC Future Ken Takashira, Molecular Gastronomy Network ...
