Because in a recipe it's impossible to specify cooking times without pre-heating. It's easy to say 10 minutes at 200 degrees, because this would be exactly the same for everyone. Every oven is different, so the time would be different depending on your oven, which the person writing the recipe can't know. So if the instructions on something like bread say pre-heat and bake for 10 minutes at 200 degrees, they know the result would be good.
There is also the fact ovens warm up differently. If there is a heating element within the compartment where the food is being heated (especially above), this element gets way too hot and emits a lot of infrared radiation whilst heating up the oven. It does this because it wants to get to the set temperature as fast as possible. Once it gets there it only needs to maintain that temperature, which is much easier, so the heating element gets much less hot during this time. If you set something like a cake in the oven with a heating element right above it, best case the top of the cake gets baked more than the rest, worst case the top gets burnt before the inside cooks.
Then there's the fact whilst heating the temperatures inside the oven fluctuate a lot, some parts get hot fast, other parts take more time. When you have food that's sensitive to that you def need to preheat.
And there's a lot of chemistry going on, for example some foods get really greasy if they don't get hot enough while cooking. Whilst these food could be cooked with the temperature going from 50 - 150 degrees, the end result would be much better if it's just cooked at 200 during the whole process.
Now there are a lot of cases where this doesn't matter and if you know your oven well enough you can compensate. But there are plenty of legit reasons to pre-heat and you may even have better results when pre-heating, even if the end result was fine before.
So I agree, people should pre-heat and there are tangible benefits!
The issue is from the element getting too hot while warming the oven up. Some ovens have features that warm the oven slower while still cooking some food correctly. Doesn’t work for baking obviously.
It winds up being a Little faster on my oven than preheat and cook. Adds about 8 minutes while preheating can be around 15-20.
when i was a kid, our ovens (🥑 green!) had a separate pre-heat setting and if you forgot to switch it to 'bake', it really messed up what you were trying to make.
Generally speaking, ovens will put out as much heat from the heating element as possible to reach the desired temperature quickly. Once at that temp, the oven maintains a largely even and consistent temperature so long as you aren't opening it repeatedly. That allows you to have the same temperature surrounding your food at all times and have predictable cooking results and timing.
If you put food in at the start without preheating, your food is surrounded by room temp air instead of heated air, yet is exposed to high temp direct radiant heat from the heating element. It will eventually reach the even temp expected, but only after several minutes of that initial exposure to the direct heat of the element. That is far more likely to lead to over cooking the surface exposed to the heating element and/or undercook the remaining surfaces and interior. It is closer to trying to bake in a grill than in an oven.
If the thing you're cooking is thin and is fine to heat from largely one side (like a pizza), your results may be acceptable if you keep an eye on it. If it is a cake or something though, it will be hot garbage, either burnt or soupy. Regardless, the cooking times on the instructions will not be remotely accurate.
I actually cook a lot and I do this. The benefits aren't very significant but it certainly doesn't ruin meals (if you cook like me lol).
It's more energy efficient and doesn't affect the food as much as you would think. Because of the temperature difference between your oven and house, and that heat rises, tons of heat flies out of the oven as soon as you open it. That is why there's the massive blast of heat from the oven when you open it, it's practically flying out at mach speed.
Afterwards there are only minor benefits from preheating the oven because the temperature has dropped significantly and it has preheated itself (and food) again anyways.
Secondly I never strictly use timers to tell me whether my food is cooked or not. Even "30 mins at 300 degrees" on different ovens will give you varied results, because built in oven thermometers are not very accurate. Additionally to make the oven look more accurate the screen will lie to you. On my oven, quickly after reaching temp, it may say "400". If I turn my oven off and on, and immediately set it to 400 again it'll say something like "325", because it's a lying sack of shit that tries to trick me into thinking it's faster and more accurate than it really is.
That's why independent oven thermometers are so popular. This is also why I gauge my food by it being cooked or not. I look at the crispyness and browning of the food. If it's a good color, I remove it. If undercooked, no shame in returning it to the oven. If the outside is burnt and the inside undercooked then that's the fault of either the recipe, cooking vessel or temperature (which is part of the recipe anyways).
Thirdly it makes managing things marginally easier. Instead of trying to optimally time your preheat as to not waste time, but also not to waste energy for 20 minutes, it's easier just to turn it on with the food in.
I hope you understand why I don't believe in the satanic oven preheating conspiracy.
Counterpoint, preheating just gives you a consistent starting point to follow their recipe. So you could follow their recipe once to see the intended result, then optimize it for your equipment (find the correct time and temp to get the intended result without preheating).
This all assumes you're cooking a frozen thing. If you're baking, follow the damned instructions. Baking is a science.
Yes, RTFM (Read The Fucking Manual) is kinda the gold standard if you're looking for consistency and preheating is what eliminates most of the difference between shitty ovens and more reliable ones.
The time it takes to go from cold to hot varies massively between ovens, and your oven might not be up to temp by the time your recipe says to pull the stuff out.
Remaining factors are keeping consistent temperature and overshoot, which is why you'll invest in a proper oven if you're even remotely serious about baking.
You know what's the real bullshit? Listing melted butter as an ingredient. Mother fucker, who keeps melted butter on hand? Make the ingredient oil, or make melting it part of the instructions!
I'm fine with melting butter, but show me where in the prices I'm supposed to do it.
The pancake recipe my wife likes me to make say something like:
Milk
Flour
Sugar
Egg
Melted, slightly cooled butter
add the lemon juice to the milk and let it thicken while preparing the dry ingredients.
Beat the egg into the milk then whisk in the melted butter.
If it was slightly cooled at the beginning it's not whiskable by the time I get to the step. If it's solid at the beginning it's not slightly cooled when I go to whisk it in (it will be straight out of the microwave)
...
As someone else said, it's an extremely small hill but I don't think you're going to push me off of it.
I don't even get how you're supposed to do that without trial&erroring melting enough in the microwave. I know butter has the measurements written on the side (in Canada/USA at least) but it doesn't help if you don't have a fresh stick of butter
As much as I want to agree with @Stamets on the basis he's a cool guy, this is an argument I can get behind.
Make the ingredient oil
As someone who can't eat butter, 99% of the time you can make this move with a neutral-tasting cooking oil. Some folks are in love with how butter changes a dish's flavor or richness, but there are many other ways to add fatty acids and glutamates to food. So it really is kind of bullshit - save time and reach for the vegetable oil.
The only exception are dishes that need the cooking fat to solidify in the fridge. Coconut oil and lard (suet too - but who has that?!) can work for those uses, but think ahead and beware of your melting points. You don't want to deliver an oily mess of food to a friend's house because it was warm out.
Remember though that butter is only 80% fat. Especially relevant for baking recipes where you have a ton of butter and if you replace that can make it denser and greasier. E.g. 200g butter you should replace with ~160g oil and 40ml water.
That means your literally half cooking your food, anything below the correct temp is generally doing nothing, so either you are messing up your final product unknowingly or realizing it's undercooked and having to leave it in the oven for longer to make up the difference.
It's not a time saver, it's just making bad food. What a weird self own.
either you are messing up your final product unknowingly or realizing it's undercooked and having to leave it in the oven for longer to make up the difference.
For frozen pizza/nuggets/etc, the cooking time is always a range. I always just put it in while it preheats and set the timer for the top of the range. Everyone's oven and preferences are different anyway so it's not like some exact science. If they're underdone, I leave them in another minute. Overall it saves time.
I used to not preheat my air fryer to make frozen pao de quiejo. It was ok, but then one day out of curiosity I did the preheat, holy shit it made a huge difference. Preheat resulted in a far better crust than using the full sized oven. True story
Sooooo uhhh, asking for a me, how does one preheat an air fryer? I feel like the one here cools off pretty much instantaneously once I open the door on it. Luckily the manual mentioned that I can just add three minutes to suggested times to skip preheating so I just do that 🤷♀️
Air fryers are convection ovens so they don't need nearly as much heat-up time as, say, ten tons of stone worth of indirectly-fired wood oven, but it's not like they spit out hot air instantly the resistive elements first have to get up to temperature.
Why not just follow the microwave instructions instead then? That's what I do when I'm hungry, lazy and impatient. Why spend 30-60 minutes waiting for food anyway just to screw up the recipe when you could have spent an extra 10 minutes to do it properly?
I never imagined 196 being such a nasty place until I started looking through this thread. How many posts need to be made, each with dozens or hundreds of upvotes, all just saying "Then your food's shit [you moron]!"
Like, damn, I'm pretty sure Stamets isn't gonna beam into these people's houses and force-feed them food cooked in a non-preheated oven. Maybe, I guess, but just stun him with a phaser if he tries it? This really seems like a non-issue of one person's preference that doesn't need a whole community piling onto it.
I don't understand the "it's just a meme" logic. I've seen it used a few times to excuse whatever the meme says.
Imagine if the meme was "Stop signs don't make sense, I've got places to be, vroom vroom"
That's stupid and dangerous advice. This meme isn't dangerous, but it is stupid.
Obviously if there was a "Sarcasm rabbit" type meme, now it makes sense. I've never seen this meme image before, maybe that's what it's going for, but for now it's going to get shit on.
"It's just a meme" is the same as "it's a joke. Stop taking it seriously, dumbass." Nobody is excusing what the meme says as actual advice. They're telling people to stop taking it as advice, because it's a joke.
Bro nobody is frothing at the mouth, they're just shit talking, because like, that's the whole point of these kind of communities. If we wanted a slideshow to scroll through, we'd go to Tumblr or something.
Would you prefer Lemmy just be a series of low-effort memes that get upvoted but never have any conversation?
Nobody is butthurt, nobody is upset, nobody even really cares. They're just taking the (admittedly unnecessary) "default tone" of the internet which is a bit needlessly combative, but that doesn't imply anyone actually cares about this topic anymore than you do. If your meme can be "just a joke; don't take it that serious," then their comments can be the exact same tone.
Relax; everyone is just bullshitting except for the people complaining about the people who are bullshitting.
for food that you make all the time where you have figured out the timing perfectly, for sure, go ahead. that saves energy.
but if you bake a cake or some shit that you don't do as often, always follow the recipe. i've had some pretty bad cakes from people who did not do what it said in the funny food book.
Leavened products, especially chemically leavened ones like cakes, need the oven to be hot when they go in for proper texture. The heat creates steam which means more and bigger bubbles, and the baking powder also reacts better at high temperatures, producing even more bubbles. And these bubbles need to start growing before the protein in the flour starts to set, otherwise they stay small and you get a dense texture.
Sometimes things come out better that way, so do as you wish. Just know that many things will come out leagues better if you do that extra bit of prep.
It really depends on what you're doing. Consider a steak: If you put it into a cold pan and heat it up it's going to be 110% done on the inside before you get to temperatures that cause browning -- the protein is going to denature at ~70C, Maillard reactions occur at about 140-160C. So rule of thumb is if you want crisp or brown anything, you probably should blast it with some actual heat.
Then, when it comes to printed recipes: While every oven bakes differently they heat up even more differently, so if you want to give a baking time including the pre-heat is going to increase the error bar quite a lot.
And then there's stuff that needs proper rituals to turn out good, bread is probably the best example: Preheat, steam, falling temperature. Sure you'll get something edible if you put some dough in a cold oven but it's not going to be nearly as good, raise strangely, have structural issues, and forget about having a proper crust.
Oh, coming back to pans: "Hot pan, cold oil", as the Chinese say, is how you make iron pans non-stick: Without preheat not only is your steak going to be soggy, it's also going to be glued to the pan. If you use a teflon pan at the temperatures needed for a proper sear you'll quickly need to buy a new one while even bargain-bin iron pans are going to last generations.
There are only few things that are really sensitive towards low temperatures - cookie doughs, soufflé and maybe bread. For any other food preheating the oven ia just a waste of energy.
Food companies only write it on the instructions because the time the food needs in the oven is not valid when they have to count in the speed your oven needs to heat up.
Am I the only one assuming they refer to the step at the start because the recipe will always take longer so I'd rather just wait for it to heat rather than set right away?
Only exception I found is bacon. Get one of those big metal baking sheets with 1-2" sides, and line it with baking paper. Lay your strips of bacon down, without them touching, and put in the oven. Set to around 425 and your bacon should be done in about 10-15 minutes once the preheat beep goes off. You figure out the time that works with your oven and bacon thickness. Memory is a little fuzzy.
I read that somewhere once and it comes out way better. Otherwise the top side never gets browned and then you try flipping them to make up for it and it sucks. This way you don't have to mess with it and the paper absorbs most of the grease. Easy to clean up.
It was just amazing as I had been preheating like all the instructions said on various sites, but it never came out amazing. Found one random comment that said to NOT preheat and stick it in cold was the magic I needed. I never liked cooking bacon on the stovetop. Throwing it in the oven is easier for me and I can do bigger batches, especially with two baking pans.