Why does oil/butter alone in a hot pan burn, but if you add food to the oil the oil doesn’t burn?

Question

Even if the pan appears to be at the same temperature

In: 1

Answer 1

Generally, the more stuff in a pan, the slower everything will burn – this is because heat always wants to go from a higher heat area into a lower heat area. If you have only butter in a pan, then the path for heat to travel is from the flame, into the pan, and into the butter, heating the butter hotter and hotter until it burns.

But add some diced onions into that butter, and now the path becomes flame>pan>butter>onion, and until those onions get to a very hot temperature, heat will continue to transfer into them, taking away from the heat added into the butter. Though, if you leave them alone long enough, their temperature will increase until they start burning.

You can keep the process going, as well. When I make minestrone, I start with onions, carrots, and celery, all sweating down in oil for a few minutes until they’re soft. Then I add more veggies to saute before I add my liquids – potatoes, zuchinni, etc. – and the new veggies absorb enough heat to slow down the cooking of those first veggies, so that nothing burns or overcooks (as long as I’m paying attention).