The Food Lab

Unraveling the mysteries of home cooking through science.

The Food Lab: How to Grill a Whole Chicken

It's time for another round of The Food Lab. Got a suggestion for an upcoming topic? Email Kenji here, and he'll do his best to answer your queries in a future post. Become a fan of The Food Lab on Facebook or follow it on Twitter for play-by-plays on future kitchen tests and recipe experiments.

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[Photographs: J. Kenji Lopez-Alt]

Look what's gone and happened: while we were busy down here on earth talking about what kind of fried chicken sandwich is ok or not-ok to eat, science has gone and put a frickin' robot on Mars, which just goes to show what can happen when there's more agreeing going on and less disagreeing. Go science!

In the spirit of agreement, I'd like to propose short list of things that we can all agree on (and if you disagree, you can just bugger off):

  • It's pointless to make Ghostbusters III without Bill Murray.
  • There are basically two schools of thought as to which type of bear is best.
  • John will always beat Paul.
  • Eating a whole chicken cooked over a coal fire should be one of the tastiest ways to spend a summer evening.

We'll take the first three as read, focus on the fourth, and come up with a sub-list of things we can all agree upon about grilled chicken in the summer:

  • Perfect grilled chicken should have crisp, crackly, blistered skin all over its entire surface with no soft spots, no pockets of blubbery rubbery fat.
  • Perfect grilled chicken should have breast meat that is moist and tender with none of the chalkiness or stringiness overcooked chicken can get.
  • Perfect grilled chicken should also have leg meat that is cooked all the way through but not tough.
  • Perfect grilled chicken should be presented as cooked—no cheating by cutting the chicken into parts. We're here as much for the great presentation as for the awesome flavor.
  • Summer is a time for spontaneity, so perfect grilled chicken on a hot summer evening should not take all night to prepare. No overnight brining, drying, salting, or any tricks like that.

The problems with grilling whole chickens are similar to the problems with roasting whole chickens. Firstly, getting the entire oddly-shaped beast to cook evenly is a chore, particularly because breast meat shouldn't be cooked past 145 to 150°F if you want any moisture left in it, while leg meat needs to be cooked to 165°F or beyond (that is, if you don't like eating pink chicken). Secondly, getting fatty chicken skin to render both its fat and moisture so that it can crisp up properly—and more importantly stay crisp—requires a bit of acrobatics.

I've always been a chicken-griller (it's my mom's most requested meal), but the past couple weeks have been a little insane. In an effort to pinpoint exactly what factors make a difference, I've grilled a dozen Cornish hens, ten fryers, and six roasters, using methods ranging from a whole bird cooked over an indirect fire, to vertical grilling (beer can chicken-style), to make-shift rotisseries. Low heat, high heat, and everything in between. Here's what I've found.

Best Prep Method: Butterflied

I've extolled the virtues of butterflied chicken in the past for oven-cooking applications, and I'm happy to report that it is just as successful for cooking chicken on the grill. How does it work its magic?

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The most important thing that butterflying does is that it exposes the legs and thighs. With a whole chicken, the thigh joints are underneath the chicken's back, insulated by plenty of fat and bone. They take a long time to cook. By the time they reach the requisite 165 to 170°F, the breasts of the chicken are well beyond overcooked.

By butterflying the bird and pressing it out flat, the legs and thighs become the most exposed part of the chicken. They pretty much automatically cook faster than the breast meat, meaning that you can get both breast and leg meat that's finished cooking—and therefore at its juiciest—at the exact same time.

After cutting out the backbone and flattening the bird, I find that running a metal or wooden skewer through its thighs and breast will keep it level and make it easier to maneuver on the grill.

Best Fire To Use: Two Level

There are two end-goals when cooking chicken on the grill. The meat needs to cook through to the center, and the skin needs to be well rendered and crisped. The order in which these two goals are best achieved is up for debate, and something I'll address in the next section.

For now, we can agree that the goals are not necessarily in harmony with each other.

See, for the moistest, juiciest meat, slow, gently cooking is ideal. The hotter a chicken cooks at, the bigger the temperature differential between the very center and the exterior. At very high temperatures, the outer layers of a delicate chicken breast will overcook, turning dry and stringy before the inner layers even have the chill taken off of them.

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On the other hand, crisp skin requires some degree of high heat. The process of skin crisping involves first removing moisture and rendering excess fat, followed by setting and browning of proteins. This last phase requires relatively high temperatures to achieve.

What this means is that in order to get both end results, you need the adaptability of a two-zone indirect fire. That is, a fire with all the coals piled up on one side. This gives you a cooler side to cook gently on, and a hotter side for crisping.

Hot Then Cool, Or Vice Versa?

Conventional cooking wisdom tells us that we should start our meats over high heat, browning the exterior and building up a crust before finishing it off gently to cook through. This approach is based largely on the outdated notion that "searing locks in juices," an idea that is so patently false that you should immediately question the value of any friend who tries to foist the idea on you.

I cooked two chickens on the exact same grill side by side. One I started over the hotter side of the grill, cooked it until crisp, then transferred it over to the cooler side to finish cooking. The other I did the opposite: cool side until it was within a few degrees of its final temperature, followed by a brief crisping session directly over the coals.

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Pockets of un-rendered fat between legs and breasts

Even before tasting or weighing the cooked chickens, I noticed that the bird that I started over the hot coals took significantly longer to crisp than the bird I started over the cooler side. This extended time over the hot coals is bound to lead to more unevenly cooked, dryer meat in the end (weighing the birds for moisture loss confirmed this—the hot-then-cool bird lost about 3% more moisture than the cool-then-hot bird.)

This is because when you place a cool bird over hot coals, it can't actually start crisping up until much of the moisture and fat are rendered out of the skin. With the chicken started on the cooler side of the grill, this rendering occurs as the chicken is slowly cooking, so that by the time it hits the hot side of the grill, there is very little moisture and fat left in the skin, allowing it to crisp extremely rapidly.

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Uneven browning and rendering in a hot-start chicken

Not only that, but the bird started over the hot side didn't crisp up evenly. Even as the skin on the breast was threatening to burn, there were still pockets of un-rendered fat in the leg joints.

The cool-then-hot chicken, on the other hand, browned and crisped evenly all over.

Skin-Up, Skin-Down?

So we know that a two-level indirect fire with the chickens started over the cool side and finished on the hot is the best cooking method. The last question I had was whether skin-down, skin-up, or a combination of cooking methods is the best way to get the crispest skin.

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After cooking through another half dozen birds, one thing became clear: If you want crisp skin, you must finish the cooking skin side down. Once the skin is crisped, flipping the bird back over is a death kiss;moisture and steam rising from the meat will quickly turn even the crispest skin soggy within a matter of moments.

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I found the ideal method is to cook the chicken over the cooler side of the grill skin-side-up with the legs facing the hotter side of the grill (to give them a little jumpstart on cooking). Once it reaches within 15 to 35°F of its final serving temperature, you'll notice that the skin around the breasts and legs has already dried out and tightened up, indicating that its moisture loss and fat rendering are complete.

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A quick flip to finish over the hot side of the grill is all it needs to reach crispy perfection. By pressing down on the back of the chicken with a stiff spatula, you can make extra-sure that all the skin gets good contact with the hot grill. (Just make sure you keep the grill covered—an uncovered grill has too much access to oxygen, leading to fat drippings that can combust and leave a sooty acrid deposit over you perfectly crisp chicken skin).

Final question: how does chicken size matter?

Pickin' Chickin'

Head to your average supermarket and you'll find three to four different size classifications for chickens. they're all great for different purposes, and choosing one depends largely on your end goals.

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Fast, Easy, and Extremely Juicy: Cornish Hens

Cornish Game Hens, contrary to their labeling, are never game, and not necessarily even hens. They are chickens under a month of age weighing under two pounds with at least one parent being a Cornish breed. For all intents and purposes, they're just really small chickens. They feature meat that is extremely tender and juicy, though not particularly flavorful.

However, a grill adds plenty of flavor on its own, so the flavor issue is not a big deal. Cornish hens have the advantage of a vastly simplified and expedited cooking method: Because of how small and innately juicy they are, you can cook them directly over the hot coals from start to finish without bothering with a two-level fire at all. I start them skin-side up, then flip them a few minutes in, letting them completely cook through skin side down.

In under half an hour start to finish, you've got crisp, juicy, tender chicken in convenient single-serving portions. It's my go-to choice for an easy chicken dinner from the grill. I can fit up to six Cornish hens on my grill at the same time.

Meaty, Good For The Whole Family: Broilers and Fryers

Broilers and Fryers are the next two sizes up and are the most common chickens sold in the U.S. 6 to 8 weeks in age, they have a good balance of flavor and tenderness, and are sized just right to feed four.

I can fit a couple of fryers on my grill at the same time, making them ideal for larger dinner parties.

Best For Barbecue: Roasters

Roasters are the largest, coming in between 6 to 8 pounds. The carcasses of mature chickens (at least 3 months old), they have a more pronounced flavor than their smaller counterparts, but are also more difficult to cook evenly because of their large volume.

Cooking a roaster is an exercise in patience. It can take up to 45 minutes or so on the cooler side of the grill before it's ready to be crisped up. This means that if you're the type of cat who likes to add some wood chips to their grill for some intense barbecue flavor, this is the chicken for you. Slow cooking gives it plenty of time to soak up that smoky flavor.

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You want the tl;dr version? Here you go:

Butterfly your chicken, season it well, start it skin-side-up on the cooler side of a two-zone indirect fire, cook it to within 25 to 35°F of your final serving temperature, flip it skin-side-down over the hotter side of the grill, and cook until crisp and cooked through. Rest, carve, and serve.

We'll be featuring a different grilled chicken recipe every day this week, starting with the simplest!

Get The Recipe!

Grilled Butterflied Chicken »

About the author: J. Kenji Lopez-Alt is the Chief Creative Officer of Serious Eats where he likes to explore the science of home cooking in his weekly column The Food Lab. You can follow him at @thefoodlab on Twitter, or at The Food Lab on Facebook.

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