Myths That Waste Energy In The Kitchen: The Baking & Roasting Episode

Sure, if you want some dry, chewy food then you can avoid the preheating.

I never pre-heat my oven and my food is never dry or chewy unless I want it to be. Maybe I have a better oven than Doug here, or maybe I'm just the better cook ;)

Preheating is especially pointless if you use the oven fan! Nothing quite as retarded as opening the door and having the fan blow all the hot air in your face. Newer ovens are smart enough not to do this, but the older ones weren't..

Preheating isn't just about cooking times. The main reason is to build even heat throughout the oven so that when you put in a couple of pies or sheet of cookies, you don't end up with crispy on one side and raw on the other. It may not make a lot of difference for roasting meat (wouldn't know, I don't eat it), but ask a professional pastry chef or baker sometime about why their ovens never get turned off.

Granted, my oven is from the 50s and I've even added a few bricks at the bottom to help manage heat fluctuation, but this rings true through most modern ovens. The best thing you can do is get a convection oven that will move the air around and pre-heat faster -- but you still need to pre-heat for at least awhile.

I never use oven, because it really spend a lot of energy. And also when you are hungry you cannot wait to heat it.

I agree with most of what you are saying here - but as a hobby baker, it would be a waste of ingredients to not preheat. Some are more forgiving than others - but breads and some cakes are not. Thats why I like to have a baking day - and do it all of those at once. =)

I am able to preheat my oven, if needed, in 6 minutes to any temperature with a beeper that goes off when it is done. I typically don't preheat as I am usually in a hurry to get things done.

I'd do it for a roast, but not anything I'd be baking. Those things are meant to start cooking in a hot oven. The chemical leaveners in cakes, biscuits, and quick-breads are time sensitive, meaning that if the batter is left too long at a cool temp, the air will escape. As for yeast, the medium temperatures in the beginning will cause the loaf to over-rise. Plus, this all messes with the suggested cooking times raising your chances of having dry/undercooked food.

I don't think the preheating trend exists in modern times as a vestige of old fashioned oven. Instead, it exists for the same reason recipes don't usually call for "handfulls" or "a good sized chunk." It's all about consistency.

A decent convection toaster oven is a great alternative to an oven altogether. I barely ever use my full size oven. It only uses a fraction of the energy and is smaller so it takes less time to come to temp. The one I have is big enought to cook a 12' pizza!

Don't worry Bram I'm quite the cook but it sounds like we should have a cooking challenge someday. Preheating avoids the issue of having the exterior cooked while leaving the interior remain cooler.

I think it would be great for Mythbusters to settle this issue once and for all.

Don't quite remember the details, but there was an Alton Brown episode where he talking about ovens. He said that it was important to keep the oven clean in order to get the food to cook evenly. Something to do with the "rays" bouncing around.

This is a poorly thought out article. Preheating is necessary for much baking. If the author just said, for these specific things, you don't have to preheat, that would have made a great "tip" but many foods require preheating - especially baking. e.g. Pizza (from dough) needs a really hot preheated oven or you end up with soggy crust.

=== author's response follows ===
Tried it both ways. Couldn't see a difference.

Liberty, we bake bread almost daily (in a gas fired oven) and never preheat... the bread comes out perfectly! The only thing it might do is dry out the bread (or other food) because of the longer baking time, but I think it takes only 5-10 minutes longer.

It is true though, for the perfect bread with the perfect crust it's better to preheat, with a pan with water inside the oven warming up in the process as well (creating a nice, moist environment for that perfect crust), but I don't think it's worth it for everyday bread... (and even much less for most oven dishes). Maybe butter-cake is the only thing that I wouldn't dare to bake in a preheated oven, since you can't even open the door without spoiling it...

I suspect that buying store-bought bread, pies, etc is actually more sustainable than baking your own. Not only are commercial ovens bigger and more efficient, but they can also be left on for extended periods (i.e there is no real pre-heat time since one set of loaves is baked immediately after another). Furthermore, there is less water used for cleaning pans. Of course, if you insist on fresh bread daily, and don't walk to the bakery, then MAYBE baking your own bread is better!

Thanks for the article -- I'd wondered but never taken the time to think about why preheating did or didn't make sense.

But I wanted to point out the method of "jump-start cooking". It combines the efficiency of microwave cooking with the golden-brown crispy texture expected from oven cooking. Works great, but takes a little practice to get the times right. But it says to skip pre-heating the oven, and instead pre-heat the food in the microwave before popping it into the oven to finish, and it's far more efficient than plain oven cooking, with or without preheating.

There is probably also a different reason why most recipies prescribe preheating: different ovens need different amounts of time to achieve the acquired temperature. A recipy without preheating would become dependent on the oven model and the surrounding temperature:

"from cold start
slow model X: baking time 25 minutes
medium model Y: baking time 23 minutes
quick model Z: bakking time 20 minutes

substract 2 minutes when in the tropics, add 3 minutes when oven stands in cold kitchen"

the traditional:

preaheat to x degrees
bake 18 minutes

is much more convenient for the recipy author

If you used your oven for 2 solid hours per day, every single day of the year, you'd only use $360 worth of energy, total.

http://michaelbluejay.com/electricity/howmuch.html

I think it's hardly worth worrying about.

You can get more bang for your buck worrying about your furnace, or your air conditioning. Appliances don't really use that much energy.

And since most people don't cook much at all these days, I seriously doubt anyone is going to hit the 2 hours per day level that I just mentioned.

For the author, who has obviously figured out how to cook where everything comes out just fine without preheating, it's a great idea.

But for anyone else who is worried about their food not turning out right, they probably shouldn't worry about it, because it's a minimal amount of energy in the grand scheme of things.

I live in the upper midwest, and it gets damn cold here in the winter. I do preheat my oven when it's cold out, because all of that heat goes right into my house, making it 100 percent efficent.
It does double duty, both to bake my food and to warm my house. I think in the zeal to paint old habits as wasteful, sometimes we forget that there's more to the picture than it seems.
In the summer I cook out on the grill to keep the house cooler.

=== author's response follows ===
Great point. Agree fully with your thinking.

Having grown up in a household full of superstitions like "don't open an umbrella in the house, it'll bring bad luck." I have always taken pleasure in disproving such. I also maintain that a decent cook has very little use for any recipe, save perhaps to scan it for a rough look at proportions and a reminder of the ingredients - and for this contrariwise approach I get plenty of compliments.

In today's culture, I'd say most "baking" is for caserole type dishes like lasagne or roasted potatoes and meats plus those pre-made frozen dough things- baking just takes up more time than most people have. If you buy this assumption (just look in the refrigerator/freezer section if you doubt the validity of it) then you can see another reason why preheating is pure bunk for the average person on an average day.

Yet another incompletely researched TH article.

The reason you preheat is to SAVE energy.

If a recipe calls for an oven temp of 375 Farenheit for 45 minutes, then the baking means it needs 375 for 45 minutes not 120 to 250 for 5 minutes then 250-350 for 5 minutes, then 375 for 35 minutes.

Individual ovens and fuels vary and, maybe your high end model heats up fast. Putting food in before the oven is ready is not adding to the cooking of the food very much at all. Really, nothing. Part of cooking is not only heating the food but also heating the oven the food is cooked in. Be it a brick oven or a high end range. It is necessary for safety and proper recipe results.

Another reason is to have even convection currents in the oven that are consistent in temperature. True with any type of oven and I don't mean just convection ovens.

So by preheating + having the food ready to go in the moment the preheat sensor buzzes that it is ready (mine does, anyhow) and also remembering to turn the oven off (which I think is much more wasteful than preheating - how many times have you forgotten? Usually when guests are present or you are tired) is much more efficient and means the food is cooked properly, safe to eat, and fully cooked so none is wasted.

It is also important to note that of all the contributers to pollution and carbon, this is the least of our worries since eating is the one last thing humans have left to enjoy and a waste of our time!

Live closer to work. Take mass transit. Bike to work. Buy a more fuel efficient car the next time you buy a car. Insulate your house properly. Make sure your exterior wall outlets are insulated. Upgrade, fix, or replace gaskets on outside doors. Save money and plan on upgrading your heating and cooling to a new system (someday). Heat pumps are great for some climates and only use electricity. My house was really hot in the summer, I studied when it was hot and concluded it was mostly radiant heat coming in via the roof. So I am installing special metallic sheets on the underside of the roof in the attic to reflect the suns heat out of the attic. This will prevent the second floor from roasting in the summer and reflect heat back in in the winter. Install other energy saving things like insulate the pipes from your tank water heater (or at least the first 5-10+ meters). If you have a water heater made in the last 10 years, it is a waste of money to add an insulation blanket. Insulating both the hot and the cold pipes will do more good.

I agree that preheating (and the "coasting" idea -- I like that!) is excellent for casseroles and dishes (don't do the roast thing, we're a veggie household).

But baking tends to be an exact science, although we use a bread machine and local ingredients (I think that would be more efficient than store-bought bread, Liam), so cakes and cookies are what we're talking about here.

And I also agree with zuzu -- baking cookies this time of year doubles up as a househeater.

We're on solar and so obsessively watch the meter, and I'd say the oven is the least efficient item in the house, second only to the dryer (and yes, we usually use a clothesline), so the coasting thing and not preheating the oven for us would mean the difference between excess kWh and not enough...

Ironic that "roasting meats" is mentioned in the article. I wonder how much energy you'd save by roasting vegetables instead vs. not preheating your oven.

This is about as insightful as the post about three-way lightbulbs being longer-lasting...

Get an oven thermometer!

Interesting theory. I'll have to try it out more often. Although there are some occasions where it is totally necessary to preheat the oven. I agree when roasting it's not as necessary.

zuzu and Pieter are absolutely right. Whether you preheat or not, you still have to heat the food as well as the oven up, which will take the same amount of BTUs and kilowatts to generate them. It's thermodynamics. You can't change that.

Also, I have to say that the bit about our 'ancestors' preheating coal and wood fired ovens is absolute hogwash. Those ovens CAME preheated. They were left burning most, if not all, of the time. You didn't let the fire go out in between meals -it takes an hour or so to get the fire going on it's own, and then you have to heat up the oven, which was cast iron! This is what my great grandmother did and I have inherited her stove. I can tell you, it's pretty heavy. And, if you go back far enough (try 1700's), I'm pretty darn sure you won't see any baking recipes that claim you have to 'preheat'. I would wager that the whole concept of 'preheating' came with the invention of the electric and gas ovens.

Which brings me to my final point: if you want to be more efficient with baking/roasting, get a gas heated oven/stove, or something solar. Electricity is not very efficient, and is dirty and expensive.

=== author's response follows ===
The waste from short term preheating comes when one opens the door to put the uncooked food in. Has nothing to do with energy mass balance per se except in the sense that opening the door after preheating requires more heat input.

With a gas oven used in summer a great deal more energy is wasted in preheating because combustion is outside of the oven chamber.

I have owned several wood/coal stoves and have cooked bread and Thanksgiving dinners with them. Your comments indicate you have very little experience cooking with one when the weather is temperate. One does not want to overheat the entire kitchen with a woodstove charged with enough fuel to bring the oven to baking temperature when it is hot out!

When placed in an outdoor "Summer Kitchen" during summer there also is no reason to burn a woodstove at high charge all day. Only when the kitchen stove is also the primary means of room heating does that make sense.

They may not have called in "preheating" but sure enough they did it. Call it unproven theory or just speculation, it matters not. Our habits develop from a starting point and do our words. Look at the number of terms for something as simple as a fry pan and you'll get the idea.

Look around the modern American grocery store in the prepared frozen food aisles. Pick any package and look at the instructions for "oven." This is how Americans cook and preheating of these has nothing to do with elegant baked goods drying out or retaining shape.

You dont know squat about cooking. Ovens must be preheated before use if you want even baking or roasting. Yes opening the oven wastes a little heat but not as much as an uninformed YOU think it looses. It is idiots like you that give pople food born pathogens and undercooked food.

There are many factors that go in to determining if preheating is needed or not, wasteful or not. If you are in the middle of a heating season any heat from your oven is useful in your home and your central heating system does not have to provide it. There are most likely many more ways you can conserve more significant amounts of energy in your home than to worry about this....besides, don't anger the chef!

While forgoing the preheat may work in most cases, it won't work for breadmaking. It's really really important to get everything on the oven heat-soaked before you put in the dough.

Yeast dies at 140 degrees. There is a delicate balance between getting that last bit of rise out of the dough, getting the crust to brown properly, and a zillion other factors. Whoever wrote this article knows nothing about breadmaking.

=== author's response follows ===
I bake break all the time. Just adjust the bake timing upward and add a little extra yeast to the dough. JL

Think of when you boil pasta - you don't add the pasta until the water is boiling because it doesn't cook properly. Many items are this way for your oven; please experiment BEFORE taking this article's advice and NEVER put pork or poultry in a nonpreheated oven, you will increase your risk for sickness (it should go directly from the fridge to the preheated oven for cooking). You preheat an oven not for time savings but for even cooking and food safety. Preheating does take less time in a gas unit than an electric one.

The author clearly has never baked a loaf of artisan bread in his life.