Why You Should Preheat Your Roasting Pan
This is good to know!
Practically every recipe you read begins with two words: “Preheat oven.” But is it truly important to make sure the oven is hot before you pop a pan into it?
The short answer is yes. Foods that are prone to collapse, such as cake, bread or anything else with flour and eggs, will benefit greatly with that little boost a preheated oven provides.
And while meals such as casseroles or pasta dishes do not require preheating, others, like meat, poultry or roasted vegetables will be even more delicious if you not only preheat the oven, but also the pan that you plan to cook them in.
Preheat the Pan for Meats and Veggies
All ovens are different. Each one has hot spots that warm up more quickly as well as cooler areas, which can result in uneven cooking. Preheating the roasting pan or baking sheet before putting your roast, chicken or Brussels sprouts in can prevent this problem. Any liquid in the food immediately begins to evaporate, resulting in uniformly browned, caramelized food.
Because the pan will already be hot, the food will begin cooking immediately when you place it in the pan or on the baking sheet, which could reduce total cooking time, as well. Also, preheating the pan does away with the extra step of flipping starchy foods, such as french fries, midway through cooking. The difference is that, on an unheated baking sheet, these foods begin to steam while the pan heats up. On a hot baking sheet, potatoes and other starchy items will skip right to crisping instead.
How to Preheat Pans
It is as simple as it sounds to preheat a pan or sheet. Just place it in the oven on the lowest rack (because most ovens are hotter at the top than at the bottom) as soon as you turn on the oven to preheat.
If you are going to grease the pan before adding food, whether you do so before placing it in the oven depends on the type of pan. For a non-stick pan or baking sheet, add the oil prior to heating it. Allow regular pans or sheets without non-stick coating to heat up until you can feel the heat radiating from it with your hand about six inches above the pan. You will find less oil is necessary as well, as the heat allows it to spread across a greater surface.
When You Should Never Preheat the Baking Sheet
There are times when preheating a pan is a major no-no. For instance, if you are baking something containing butter, such as cookies, the pan should be as cool as possible before use to prevent the dough from spreading.
If you make bacon in the oven and want to render the fat to use in other dishes, starting with a cold pan will allow the fat to release more slowly. The bacon will build up delicious flavor and crispness while producing grease you can save for later.
[H/t: The Kitchn]