We have likely heard before about the importance of preheating our pans before cooking. But why is it important? What are the benefits of it? What happens if we don't do it? And are there any scenarios when we don't have to preheat our pans? All of this and more as we look at why it's important to preheat your pan.
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Why Is It Important to Preheat Your Pan?
There are a few different reasons why it's important to preheat our pan before cooking. The first one is that when we cook something we generally want to transfer heat from the cooking surface to the item being cooked as quickly as possible. Starting with a room temperature pan prolongs this heat transfer and can lead to food like a steak being overcooked. It also causes things to take much longer to cook.
Forced Evaporation
Another reason why this is important is for forced evaporation. Let's say we are making a stir-fry and we don't preheat our pan. What's going to happen? As the pan slowly heats up, and in turn slowly heats up the vegetables, they are going to lose some of their liquid. Because the pan isn't hot enough this liquid isn't going to evaporate on contact. It will instead pool in the bottom of the wok and steam our vegetables.
This is also part of the reason why we add vegetables in stages when cooking a stir-fry. We don't want to cool the pan down for risk of the same thing happening.
Searing
One final reason why it's important to preheat our pan is for searing. When we cook meat, for example, we want a nice even sear on the surface. This develops flavour, colour, and texture. On top of that, it helps to prevent our meat from sticking to the pan.
If we start a steak in a cold pan there is a good chance it is going to stick. Same with the barbecue. It is much less likely to happen if our pan was hot when the steak went in. For more on getting a great sear on different cuts, take a look at my chef's guide to cooking meat.
The Science Behind Preheating
Understanding why preheating works comes down to a bit of basic science. When a pan is heated to the right temperature before food is added, a few things happen:
- The Maillard reaction kicks in immediately. This is the chemical reaction between amino acids and sugars that creates that beautiful brown crust on meat, vegetables, and bread. It requires high heat, and it happens much more efficiently on a preheated surface.
- Proteins seize and release. When meat hits a hot pan, the surface proteins contract and then release from the pan, which is why a properly seared steak won't stick. On a cold pan, the proteins bond with the metal before they have a chance to sear.
- Oil behaves differently. Oil added to a hot pan becomes thinner and flows more freely, creating a better non-stick barrier. Cold oil in a cold pan can become gummy and actually cause more sticking.
These are the same principles that apply whether you are cooking a pork chop, searing scallops, or getting a nice char on vegetables.
When Is It Not Necessary to Preheat?
There are a couple of instances when it isn't important to preheat our pan.
When we cook bacon, and we want it crispy, starting in a cold pan and gradually heating it up is the way to go. This renders the fat out of the bacon, which the bacon then cooks in and gets very crispy. This is also one technique for cooking duck breast, although duck breast can be started in a hot pan as well.
A cold pan can also be used when sweating vegetables. To sweat vegetables, we actually want to draw the liquid out of them. This would be done when making a rice pilaf for example. You sweat the vegetables prior to adding the rice in order to draw as much flavour out of them as possible. Usually, when sweating vegetables we want to avoid colouring them.
Finally, when caramelizing onions, starting in a cold pan is the way to go. Again, this draws moisture out of the onions, which then aids in the caramelization process.
How Hot Do We Want It?
How hot do we want our pan? It really depends on what we're cooking:
- Steak: We want the pan really hot, especially if we want it cooked rare to medium.
- Fried eggs: The pan should be hot enough that our butter is foaming but not burning.
- Stir-fry vegetables: We want the pan to be as hot as we can get it.
- Sautéing onions: Generally heated over medium heat is what we are looking for.
A good rule of thumb is to hold your hand a few inches above the pan. If you can feel strong, radiating heat, you are in the right range for most searing and stir-frying. For gentler cooking, the pan should be warm to the touch but not intensely hot.
Frequently Asked Questions
How do I know when my pan is hot enough?
The water droplet test is the simplest method. Flick a few drops of water onto the pan. If they sizzle and evaporate almost immediately, the pan is ready for most cooking. If the water beads up and rolls around the surface (called the Leidenfrost effect), the pan is very hot and perfect for searing.
Should I add oil before or after preheating?
For most cooking, add oil to the pan after it has been preheated. This prevents the oil from breaking down and smoking before you are ready to cook. The exception is when you are seasoning a cast iron pan, where the oil goes in from the start.
Does preheating matter for non-stick pans?
Yes, but with a caveat. Non-stick pans should be preheated on low to medium heat only. Overheating an empty non-stick pan can damage the coating and release harmful fumes. A minute or two over medium heat is sufficient for most non-stick cooking.
Final Thoughts
Preheating your pan is one of the smallest changes you can make in your cooking that yields one of the biggest differences. It costs nothing, takes barely a minute, and the improvement in flavour, texture, and colour is immediately noticeable. Next time you step into the kitchen, give your pan a head start -- you will taste the difference.
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