Water starts evaporating at 100c and oils and fats have a smoking point (equivalent form of evaporation) which is a lot higher and will vary depending on the purity of the oil and fat.

If you are cooking a curry with water, oil, fat and solids in a pot on a stove, should we expect all water will evaporate before anything happens to the oil and fat or might there be scenarios where the the oils and fat are evaporating before or during the waters evaporation while cooking?

  • $\begingroup$ This is a chemistry based comment, but if your recipe includes emulsions, such as milk, how would those be treated. Would the rise in temperature split them back into oils and water? $\endgroup$ – user171879 Oct 13 '17 at 22:16

The temperature is related to the average kinetic energy in the substance. Throughout there will be molecules with a range of energies above and below. Eaporation occurs when molecules at the surface boundary between liquid and air get enough velocity in the appropriate direction to break free of the surface. Since the liquid is bubbling and boiling away there's always going to be a mixture of molecules at the surface boundary and there's a finite possibility/probability for any molecule at the surface to get its required break free energy.

So no you never will get 100% purity just from evaporation / distillation.


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