The answer is a bit...nuanced.
This summer has been especially hectic for me, and whenever I’m roasting veggies for lunch or dinner (something I do often), I’ve found myself putting them in the oven while it’s still heating up in an attempt to cut down on cooking time. But then in the shower the other day (AKA where I do my best thinking), I had a realization that maybe this isn’t the greatest idea, because maybe it screws up the total cooking time and cooks the food unevenly. Or maybe it’s ok with simple foods like veggies, but unadvisable with trickier things like meats?
This mid-bathing epiphany lead to a rabbit hole of questions that lead to an internet search that somehow lead to even more questions. So I decided to consult the IRL experts (sorry, Google) to settle the issue for good.
The verdict? “Preheating the oven before putting the food in the oven is usually only necessary with foods that need to start with a certain level of heat right from the start,” says Claudia Sidoti, head chef at HelloFresh.
And what are such foods? Here, Sidoti and Ian Rynecki, executive chef for Pippin Hill Farm & Vineyards in Charlottesville, Virginia, break it down.
Let’s begin with the food that started this whole debate: veggies. Although exact oven temperature is not as important with veggies compared to other dishes (more on those later), it’s still a good idea to fully preheat your oven before sticking in your sheet of produce, says Ryneck. “Other chefs may disagree with me,“ he caveats, “but this is my recommendation if you want the best tasting outcome.”
He even takes it one step further. “I would also put the sheet pan in the oven as it preheats,” says Rynecki. Then, when the oven has reached the correct temperature, “pull out pan, pour on the veggies and hear them sizzle.” The hot pan rapidly brings up the temperature of the veggies, which ultimately helps them caramelize better. That’s important because “the caramelization is the flavor,” he explains. So while my sticking-the-veggies-in-while-the-oven-is-still-heating trick may certainly have saved me some time, Rynecki validates, it came at the cost of flavor. Time vs. flavor...sounds like I have my next mid-shower debate topic.
Anything with eggs—like strattas, frittatas, quiches, and so on—warrants a preheated oven, says Rynecki. Just like you wouldn’t begin hard boiling an egg in cold water, you wouldn’t want to put a baked egg dish into a cold oven. The reason baked eggs need a high starting temp: “A low temperature at the beginning won’t allow for the fluffiness to occur,” says Rynecki. A baked egg dish without the fluff? No. Just no.
Bread is yet another example of food that needs a properly preheated oven. When you put bread dough into a preheated oven, that quick hit of heat helps to complete the yeast’s rising process, says Rynecki. Sticking bread dough into a cold oven that gradually heats up will produce bread that is still edible, but not as delicious as it could be, he says. A fully preheated oven provides that “last 5 percent” that can elevate good bread to great bread.
And in general, anything that needs to rise—bread, biscuits, egg dishes, etc.—will require a fully preheated oven, says Rynecki. So put your patient pants on if you’re attempting such recipes.
All forms of pastry should be placed in the oven when—and only when—it’s at the exact required temperature, says Rynecki. That’s because these items rely on an initial blast of heat to help cook them evenly and also fluff-slash-rise properly.
Take biscuits, for example. If you stick a tray of biscuit dough into a not-yet-hot oven, the bottoms will get burned before the tops are fully cooked because the heat didn’t hit them evenly and instead came up slowly from the bottom, Rynecki explains. A burned-yet-gooey biscuit sounds both terrible and wholly confusing.
For another unsettling example, let’s consider cookies. “If you add something like cookies into a colder oven, they’ll come out flat and dry,” says Sidoti. That (almost) sounds worse than the botched biscuits.
In general, roasts that are going into the oven for a long period of time and a low temperature (say, 310 degrees and below), don’t require preheating, says Rynecki, since the cooking process is more about “low and slow” than delivering a quick, hot blast. In general, it’s also ok if you do want to preheat the oven for these items. “It won’t make much of a difference,” he says, “as the total cook time is fairly long and the oven temperature is relatively low.”
The exception: braised meats. Bringing up the heat slowly by sticking your meat in the oven and then turning it on helps the meat fibers break down at a better rate than if you were to stick the meat into an already hot oven, explains Rynecki.
Other Tips to Ensure Quality Cooking When Using an Oven
The aforementioned pre-heating procedures, as important as they are, aren’t everything, explains Rynecki. There are additional things you can do when using an oven to ensure your food is cooked as deliciously and thoroughly as possible.
For one, keep the oven door shut throughout the cooking process, says Rynecki. Every time you open the oven door, you decrease the internal temperature by 25 to 50 degrees, which ultimately just adds to your total cooking time because the oven then has to reheat itself. Instead, keep your oven window clean so that you can monitor the status of your food from the outside.
RELATED: How to Clean Your Oven the Right Way
Another tip: consider buying a thermometer to place inside your oven, especially if you have an older oven, like the ancient furnace that occupies my kitchen. Why? Over time, many ovens will lose their ability to calibrate the temperature, which means that the temperature you program your oven to may not be the actual temperature inside.
For example, you may set your oven to 350 degrees, but it will only climb to 325 degrees. This can make a big difference in the quality of your cooking and baking, especially with dishes that require very specific temperatures, like the aforesaid pastries, bread and egg dishes. To ensure exactness in your oven temps, get a thermometer that you either leave in your oven permanently, or one that you put in and remove with each use.
And lastly, buy a quality sheet pan with high-grade steel, which will better withstand high temperatures. Low-grade steel will bend under high temperatures and won’t be able to retain heat as well, which will translate into your food cooking at a lower temperature and thus taking longer to cook. “It may sound ridiculous to spend $30 [or more] on a single baking sheet, but it’s totally worth it,” says Rynecki.