Cooking 101: Using Heat

grillingCooking is about heat.  Being able to control heat , understanding how heat enters food, and what happens to food when it does, is a fundamental skill to master if you want to learn to cook. Fortunately, once you’ve got an understanding of what’s going on, it’s not that hard to figure out.

If you’ve cruised around this website much, you’ve probably gotten the picture that I have a horror of things that are burnt on the outside and gelatinous raw in the middle – that’s because figuring out how to use heat was one of the biggest hurdles I had to jump in order to become a decent cook.  For me, figuring it out it was a lot of trial-by-fire (sometimes literally).

I’m willing to bet that the #1 reason people struggle with cooking is the inability to control heat which stems from a lack of understanding the basics of what it is and how to use it.  I myself struggled with this for a long time – sometimes I still do if I’m not paying attention – but I hope that this post will shed some light on a few techniques that will improve your hand in the kitchen.

To get started, let’s get some definitions out of the way:

Types of Heat Transfer

  1. Conduction happens when heat is transferred through direct contact.  Thermal energy (the jiggling of molecules) being transferred through molecular contact.  This usually happens pretty quickly.  So, for example, if you have something with a lot of thermal energy stored in it (say, a hot cast iron skillet that’s been sitting on the stove for a few minutes), and a good conductor (say, olive oil), and you throw a steak on there, it’s going to cook pretty quick; i.e., a lot of the thermal energy stored in that skillet is transferred rapidly to the outside of your steak.
  2. Convection is when molecules that that have a lot of thermal energy trade places with ones that don’t, and take that energy with them when they move around.  For example, if you’re trying to boil some water on the stove, the molecules closer to the heat source will have more thermal energy transferred to them than the ones that are farther away.  If you stir a pot as it’s reaching boiling temperature, the whole thing will come up to temp more quickly.
  3. Radiation is when heat waves (i.e., infrared waves, or microwaves) penetrate a material and cause thermal energy to build up inside the material.  For example, when you throw a steak or a burger on the grill, you’re probably getting a little bit of conduction from the hot grill grates as it comes into contact with the food, but the majority of heat transfer into the food is coming directly from the heat source – your charcoal or your gas flavor bars.

Techniques Using Heat

There are a lot of ways to transfer heat into food: Steaming, boiling, sous-vide, sautéing, baking, smoking, broiling, grilling, pan frying, deep frying – even microwaving – but the thing is that most of these techniques fall into one of three categories:

  1. Low and Slow.  Low cooking temp, long cooking time.  Primarily radiation in the form of infrared waves and convection.  This includes techniques such as baking and smoking (which is essentially baking something in the presence of smoke; smoke does little to aid in heat transfer, but it does impart a wonderful flavor).
  2. Hot and Fast.  High cooking temp, short cooking time.  Conduction and radiation.  This includes techniques such as broiling, grilling, sautéing, pan frying and steaming.
  3. Immersion.  Medium cooking temp, medium cooking time, requires liquid.  Primarily conduction; includes boiling and deep frying.

As I discussed in last week’s Technique of the Week, the key to cooking almost anything is to get it to come up to temperature evenly and uniformly throughout – whether it be a 4lb roast beef in the oven (baking) or some minced onions in a frying pan with some oil (sautéing).

Okay, so, how is any of this useful?  Because precise heat control means precise cooking.

Example #1 If you’re going to cook a 4lb roast, you’re going to want to sear it using conduction (i.e. broiling or grilling), and then use radiation (i.e., baking) to bring it up to the desired temp in a uniform fashion.

Pro Tip:  Think of your grill as an oven.  Always use the ‘two-zone’ technique – one side for hot-and-fast conduction, the other side for low and slow radiation.

Example #2  Let’s say you’ve got some burgers you want to throw on the grill.  No need to low and slow them – just use high heat and a good conductor (cast iron skillet), or a lot of radiation (hot grill).  See 8 Tips for Making the Perfect Burger.

Example #3  Let’s say you’re making chili.  You’re essentially using immersion – you’ve got a lot of liquid in the pot, and it’s going to boil down over time to the desired thickness.  You’ve got to watch the heat, because as the chili thickens up, it will absorb heat more easily.  If you’re not careful, conduction will take over and you’ll burn stuff to the bottom of the pot.

Remember, practice makes perfect.  I’ve burned or under-done my fair share of things, but once I got the hang of controlling heat and more often than not using a 2-stage process (searing in one phase and essentially baking in another phase) everything became easier.  Hopefully this will make it easier for you too.

Otherwise, we’re all just stuck eating salads.

Good luck!

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*The cover photo and featured photo for this post: courtesy en.wikipedia.org s.v. ‘grilling’

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