Why do we preheat the oven?

Depending on the type of oven some ovens get up to heat by over heating till the thermostat registers the needed heat. Others take the slow and steady approach. Not only that if you start with at cold oven it definitely won’t cook the item by the end of the cooking time. Because all ovens reach temperature at a different rate of time depending on elevation and humidity.

Ovens heat up at different temperatures and speeds, and preheating allows you to have a uniform temperature to start at. I think that, as you said, the main reason for this is to make “repeatable recipes”.

But also, some dishes require a high temperature immediately, so if you were to put it in as it warms up it would cook wrong. When making a frozen pizza it might not matter, but it is key in baking fancy dishes.

If you don’t heat up the oven the oven is at room temperature. If you just put the food in like that it won’t cook right because it wasn’t in the right heat conditions for the right amount of time. So yes it would be un-evenly cooked. Food runs in my family we own a business and I know. The recipe asks for pre-heating of the oven because to be properly cooked it needs to be at a certain temperature for a certain amount of time

Technically, you can’t preheat an oven, you can only heat it. Preheating would involve heating the oven before you heat the oven, which would be quite a trick.

hahahahhahaha astrochuck that was one hel of an answer

pssst, can’t you say that about any pre?? you can’t be predisposed, only disposed?? not prehistoric, only historic… isn’t that the point of a prefix <—- ahh look I found one that doesn’t work… it was predetermined

It isn’t only a question of repeatability, though; it can actually affect the result. Putting food, a ball of dough for instance, into a hot oven will cause the exterior to be exposed to more total heat energy over the time it takes to cook the center of the ball.

If you put the dough in at the beginning of the warm-up, the center will cook sooner in relation to the crust. To build up a decent crust, you’ll have to leave the dough in well beyond the point that the center has cooked, which will dry the whole thing out more than necessary.

I have found that roasting meats and covered roasters or casseroles are fine started in a cold oven, but cake, cookies and other “open” baking of things that require the food to rise or bake quickly need a pre-heated oven.

Also, the longer the total cooking time, the less it will matter.

The side effect would be that you start cooking once you put the food in the oven and if you start with a cold oven, you run the chance of having food that is underdone, or having to put it in longer than necessary and drying the food out, or ruining it altogether. I however am an expert cookie burner, I can make everything else in the oven and broiler, but when it comes to a cookie, they burn before I put them in the oven!