Ex: Cooking 2 pizzas (same temp/time needed) in the oven at the same time. Can I just set the same temperature and time as cooking one, and they’ll both come out perfect still? Why or why not? (Let’s ignore differences in cooking based on which rack the pizza is on lol)
I don’t cook much lol, so I’m trying to wrap my head around how cooking “consumes(?)” heat energy. More food mass isn’t going to *reduce* the temperature in the oven or anything… is it? And, the food masses aren’t connected, so not sharing heat distribution(?), so that seems like they shouldn’t affect each other?
In: Physics
More mass takes more energy to heat. So yes more pizza means more energy. If your oven burner can output enough head to keep up, the time should be the same. If one pizza requires the oven burner to run constantly to maintain the target oven temp, more pizza will overwhelm the burner and it won’t maintain temperature properly (cook slower).
Soo, it kind of depends.
The main limit on how quickly your oven heats things up is heat *transfer*. The transfer of heat from the air in the oven to food is pretty slow. Your oven should be able to generate heat a lot faster than a pair of pizzas, or most other things you’re likely to put in there, can absorb.
*However* there are two important exceptions.
First: steam. Steam *will* absorb a lot of heat from the air. Your pizzas heat up, they generate steam, this steam sucks heat from the air in the oven. (Whereas if you were baking cookies, this won’t be a problem.) Just to confuse things, this can potentially make stuff cook *faster* but at a lower temperature – because that steamy air is also better at transferring heat to whatever’s in your oven.
That’s not what you want for a pizza though. You might notice a pizza on the top shelf browns more slowly (browning needs high temperatures), or even comes out a little soggy. (I’d recommend a higher temperature for two pizzas than you’d use for one. Sometimes it can be worth opening the oven door briefly during cooking to let some steam out, even though this lets cold air in, and perhaps swapping them round mid-cooking.)
Second, putting more stuff in your oven affects the air circulation. The details of this will depend on your oven and what you put in there, but you might make it hard for hot air to evenly reach everything you put in there. (Eg. if you put your pizzas on two large baking trays.)
In the microwave, yes, twice as much requires twice the time because the energy induced by the mw is distributed between two pizzas instead of one.
In an oven, no longer, because the oven keeps the temperature the same, eg, 400 degrees all the time.
> And, the food masses aren’t connected, so not sharing heat distribution(?), so that seems like they shouldn’t affect each other?
The oven heats the air, which heats the pizza. So if pizza one absorbs a lot of heat from the air, pizza 2 will not be able to receive that heat from the air.
Or you can think about it in terms of energy. A Calorie (like what’s on food labels) is the energy required to heat 1 kilogram of water by 1 degree C.
So if you want to boil a kilogram of water in the oven from 20 C to 100 C, it takes 80 Calories of heat energy (not counting what’s wasted heating air and metal).
If you wanted to boil 2 kilograms of water, then it takes 160 Calories. Or if you keep the energy output fixed at 80 Calories, you’ll heat both kilograms of water to 60 C.
So yes, adding more stuff to the oven means it will cook slower IN THEORY.
In practice, the difference is usually negligible.
1. Tons of energy is wasted heating the air, oven insides, plus whatever leaks out. So going from 1 pizza to 2 pizzas takes maybe 10% more energy, not double.
2. The oven is temperature-controlled, not energy-controlled. So if you set the oven to 350 F, it will keep adding heat until that temperature is reached. Extra mass in the oven just means the initial heating is slower.
3. For most foods, the initial heat is a small portion of the overall cooking time. Like maybe it takes an extra 5 minutes to heat a lasagna that’s going to bake for 45 minutes.
TL;DR technically yes, putting more food in the oven would cook slower, but it usually matters less than which rack you’re cooking on. The effect would be more noticable if you cooked something for a short amount of time (like some pizzas) or if you had a smaller oven (like a toaster oven).
Yes and no.
Yes at the most absolute scientific level, it will take ever so slightly longer to cook 2 pizzas than 1.
No in the practical sense as the difference is entirely negligible.
You might have a point if you need to absolutely cram your oven with huge frozen casseroles in every available inch, but also, you simply wouldn’t do something like that lol
You would have to put a gigantic block of steal in the oven for it to overwhelm the burner. Two pizzas is well within the output of your oven.
It depends.
If we assume you’re cooking with wood, and one piece of wood burning cooks one pizza in 10 minutes…
If you add another pizza but the same 1 piece of wood, it’ll take longer.
But
If your electric or gas stove automatically adds another piece of wood (aka more energy to the element or higher gas flow), then the time will be the same, but the energy cost will be higher.
Think of it in terms of energy.
The pizza maker says it takes 10 minutes at 200c. What’s really happening is that for 10 minutes, the energy in a 200c place is going to the pizza. This energy makes it ok to eat.
But 2 pizzas means the energy is going to two places.
Now, there’s enough energy that the two pizzas don’t need twice the energy- some that would’ve been wasted otherwise goes to the second pizza.
But overall you still need a bit longer, to ensure there’s enough energy going to the two pizzas to cook them properly.
So let’s say you warm your oven to temp. Then you open the door and the temp drops and you put in your frozen fish or whatever. Then 5 minutes later you open the door again and add your frozen fries cos they take 5 minutes less. Yes everything is gonna take longer to cook. Your oven temp is way down cos of the door opening twice. It’s using up energy heating frozen products. And the steam generated from the frozen products is also sapping energy from the whole equation. Plus if you have stuff on the middle and top shelf then the hot air circulation is going to be impacted. It all adds up and generally not accounted for in the cooking guidelines. That’s why they are called guidelines.
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