An investigation into the best way oils behave on sizzling, flat surfaces has uncovered the method liable for meals sticking to non-stick frying pans.
I like the opening line to this new paper, revealed right now in Physics of Fluids: “Right here, the phenomenon of meals sticking when frying in a frying pan is experimentally defined.”
Concise and straight to the purpose, as is the reason: “thermocapillary convection,” in line with the authors, Alexander Fedorchenko and Jan Hruby, each from the Czech Academy of Sciences.
That is very highly effective information. The subsequent time this occurs whereas cooking, you possibly can shake your indignant fist on the stovetop and say, “curse you, thermocapillary convection!” It’ll be a really satisfying second, not simply because you’ve got a elaborate new time period at your disposal, but in addition since you’ll have full consciousness of what it really means.
For his or her experiment, Fedorchenko and Hruby, specialists in fluid dynamics and thermophysics, examined two non-stick frying pans—one coated in ceramic particles and one coated with Teflon. The surfaces of the pans had been coated with a skinny layer of sunflower oil, after which, utilizing an overhead digital camera, the scientists measured the velocity at which it took dry spots to kind and develop because the pans had been heated.
The scientists seen that, because the pans had been being warmed from beneath, a temperature gradient appeared throughout the oily movie. This in flip created a floor pressure gradient, which directed the oils away from the middle of the pan and in the direction of the periphery; liquids with excessive floor pressure pull extra forcefully on surrounding liquids in comparison with liquids with low floor pressure.
This is a superb instance of thermocapillary convection at work—a phenomenon wherein a floor pressure gradient forces a liquid (on this case, oil) emigrate outwards. As soon as this occurs, meals is extra apt to stay to the middle of the pan, the results of the “formation of a dry spot within the skinny sunflower oil movie,” in line with the examine.
Fedorchenko and Hruby really created a components to calculate the “dewetting fee,” which measures the velocity of receding oil droplets. Very cool, however the phrase “dewetting” is one thing we don’t want in our lives proper now. The scientists additionally recognized the situations that result in dry spots, ensuing within the following recommendation:
“To keep away from undesirable dry spot formation, the next set of measures (and/or) ought to be utilized: rising the oil movie thickness, average heating, utterly wetting the floor of the pan with oil, utilizing a pan with a thick backside, stirring meals usually throughout cooking,” the authors write.
Wow. Don’t find out about you, however for me that’s all blazingly apparent recommendation (to not point out how the primary and third gadgets on that record are mainly the identical factor). Aside from utilizing pans with a thick backside—I didn’t know that. However to be truthful, I usually used a forged iron pan when frying meals, so I need to’ve subconsciously felt this to be true.
Anyhoo, that is all making me very hungry, so I’m going to finish it proper right here, head to the kitchen, and do my greatest to grasp the idiosyncrasies thermocapillary convection.