Originally Posted by foodguy
that's not quite what i was saying. what i was saying was that the effect of higher btus is to let you get to searing temperature more quickly, not to give you a better sear. The other issue is that in most kinds of cooking, the pan is not the final conductor of heat ... it's the cooking medium (water or oil). With water, it's clear ... no matter how many btus you pump into the pan, the temperature is never going to get above 212. with oil, it's not so clear. but most cooking oils have smoking points in the 400-degree range, so effectively you're never going to get the pan much hotter than that. at least that's how it seems to me.
I agree with your point on water. The beautiful thing about latent heat is that as water reaches its boiling point (212F) you can keep pouring heat in and the water doesn't keep rising in temperature, even before it boils away. So when you add food, provided you've added enough heat and kept it at a steady boil for a while, the heat that is sucked up by the food that's been added doesn't necessarily reduce the water temperature - that's the latent heat going into the food. With oil, the reaction is much different. Smoke point is not boiling point, and I don't honestly know if the oil holds its smoke point temp like water holds its boiling temp. But unlike water, which you can keep at a boil before adding the food, you can't keep heating the oil - it smokes and smokes. So when you add the food, inevitably the temperature of the oil drops because some of that heat is soaked up by the food. But there's a reason you had the oil at a certain temperature - that's the temp you wanted to get the right sear going. Now, you can just wait (with a low power burner) for the oil to come back up to temp, but that can take a while, and all through that waiting time the food itself is cooking, albeit at a lower temp than desired. In deep frying, you want that outer browning reaction happening at the surface of the food, and you also want the inside of the food steaming from its own water content. The result is the inside cooks appropriately and quickly, without too much of the oil penetrating the food itself. The result is a nice, well-cooked fry that isn't overly oily, soggy, or otherwise overcooked in the middle. So it's important that the oil temp revert back to its optimal temp very, very quickly. As you've pointed out, this is especially important in Chinese cooking, where vegetables are meant to retain their crispness without too much oil absorption. It's why most people's attempts at Chinese food can't possibly rival their professional counterparts. But I've seen other foods cooked in a similar fashion - cauliflower is wonderful when it's been flash sauteed at high heat for a short time. You can
achieve that with a low-power burner, but you can only saute a very small batch at a time. The same holds for any kind of deep frying. Anyways, we've strayed awfully far from the main point, which is that technique is most important and just buying the fancy equipment is no substitute for knowing what you're doing. But all I'm saying is that, in particular for deep frying and flash sauteeing, the only substitute for the raw power of a high BTU burner is to cook in very small batches. EDIT: actually, the more I think about it, the more I think I'm wrong about the latent heat in water. The latent heat is going towards transforming some of the water into steam. The water that's left isn't "storing" the heat, so no matter how long you keep the water at a boil, the temp will still drop when you put cold food in. This really only means that having a high heat source that restores the temp quickly is also important for poaching and boiling as well as frying.