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Burger recipes and cooking tips from J. Kenji López-Alt.

The Burger Lab: How to Shape a Burger For Grilling or Broiling

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 for play-by-plays on future kitchen tests and recipe experiments.

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Golf ball burger = no good. [Photographs: Kenji Alt]

There is nothing funny about this picture. This burger suffers from a serious disorder. It's unfortunate fate is to have been burdened with a bad case of golf ball syndrome, a terrible affliction that affects millions of grilled or broiled burgers every year. And the truly scary part? It's been directly linked to weight. In fact, according to some expert's* estimation, burgers weighing 6 ounces or more, have a nearly 80 percent chance of developing this disfiguring disease at some point in their time on the grill.

*Me

Symptoms include but are not limited to the following:

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Here's to all of you medium burger fans!

  • Soggy Bottoms: This develops when the eater is forced to squeeze the buns together in order to compress the patty to a mouth-friendly girth. Juices squeeze out and saturate bottom bun. High chance of TBF (Total Bun Failure).
  • Bun Gap: Burgers leave a large gap before the edge of the bun, requiring the eater to have several meat-deficient bites, despite having carefully measured and sized the patty before cooking.
  • Thickness Approaching Width: The burger bulges in the center, leaving the eater with a shape that is both awkward for the hands, and for the mouth. In extreme cases, burgers may reach near spherical proportions.
  • Dry Matter: This symptom is too gruesome to show in photographs. It occurs when the griller notices that the burger is beginning to acquire a golf-ball-like shape halfway through cooking. They respond by pressing down on the patty with the back of a spatula. Fat and juices fall into the flame and ignite. The result is a flat, dry patty, singed on the outside with a heavy deposit of black soot from the burnt fat.

All in all, this is a state of affairs that should largely be avoided, and luckily for us, it's indeed quite avoidable, as this burger here demonstrates:

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Let me cut straight to the chase: All that you need to do to prevent this from happening is to compensate by shaping your patty a little wider than the bun to begin with, and making a shallow dimple in the center of it. Once cooked, it should fit the bun perfectly, and lay completely flat. This cross-section below should give you a good idea of how it's done.

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The top burger was formed in the standard disc-shape and made to exactly the same width as the bun. The bottom patty was formed a little wider, and with a dimple. Once cooked under the broiler, the disc-shaped burger turns into the fat 'ol burger you see at the very top, while the dimpled burger produced the flat finished product seen above:

Now there's nothing new about that technique—pretty much any reputable book or website on burgers will mention it. And if this technique is all you get out of this week's post, then the world is a slightly tastier place. But at the Burger Lab, we don't just like to know that something works, we like to know why it works.

Hot Air

The typical explanation goes something like this: Burger starts cooking. Exterior gets seared. Interior starts heating up, forming hot air and steam. Steam and hot air build up. Burger puffs like balloon.

Hot air indeed. The theory doesn't make sense on several grounds. For one thing, why is it that this puffing business only occurs when you grill or broil a fat burger, but not when you pan sear a fat burger? It's true! The burger below was shaped exactly the same way as the puffy burger at the top of the page, but rather than broiling, I pan fried it:

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The slightest bit of puffing occurs, but nowhere near the levels of the broiled burger.

For another thing, this whole "trapping steam" doesn't make much sense to me either. We've already demonstrated several times in the past that searing even a solid piece of meat like a prime rib roast will not "seal in" any internal juices. So what chance does a loosely packed burger have of trapping in steam? About as much chance as my recently deceased cat has of trapping another mouse.

So what causes the bulge, and why does it only occur when you grill or broil the patty?

Battling the Bulge

My first question was a basic one: Is the burger actually expanding, getting thicker, or is it just an illusion?

To figure this out, I decided to measure both the thickness of my burger, and its circumference pre- and post-broiling. The thickness was measured by inserting a wooden skewer into the patty and drawing a small line right above where the burger ends. I measured the circumference by wrapping the perimeter of the burger with a piece of string, which I cut off exactly where the ends met.

After broiling the burger to an internal temperature of 130 degrees, I inserted the same skewer and wrapped the burger with the same string.

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Well that proves it—the burger is in fact not bulging, but it does lose a significant amount of its circumference—a good 1.5 inches or so.

But wait a minute—everything I know about meat cookery tells me that meat contracts when you cook it. The hotter it gets, the more it shrinks. It makes sense that the circumference of the burger should shrink, but why is my burger still the nearly the same thickness at the center? Shouldn't it have shrunk in that dimension as well?

That's when I realized that the key to this whole thing is that burgers only undergo this phenomenon when cooked on a grill or under a broiler—both methods in which the vast majority of cooking is accomplished through radiation—the transfer of energy directly through space via electromagnetic waves. Pan frying, on the other hand, cooks a burger primarily through conduction—the transfer of energy from one material directly in contact with another. What does this mean for the way the burger cooks?

Well in a pan, since only once face of the burger is actually in contact with the metal, it cooks fairly evenly across that plane, and the sides of the burger barely get cooked at all. I'm sure you've all noticed this when trying to pan sear fat burgers—crust formation on the sides of the patty is minimal at best.

On the grill or under the broiler, on the other hand, radiation reaches the sides of the patties as well, heating and browning them far more efficiently than a pan ever could. This was the clue I needed.

Above and Below the Belt

Back when my dad was on the verge of becoming overweight, rather than loosening his belt up a few notches, he'd continue to wear it at the same hole, under the false assumption that it'd keep his belly in check**. Of course, we've all seen the results of similar attempts: The belly has nowhere to go but up and over. Similarly, in the burger, as the sides of the burger rapidly cook via radiation, they contract like a belt. The center of the burger has nowhere to go but out. So even though it does lose some thickness as it cooks, the cinching up of the sides of the patty compensate by squeezing and forming the bulge.

Since a pan-seared burger heats only from the top and bottom, the sides don't cook much, and the bulging is not an issue.

**By the way, my dad has since then successfully lost the weight.

Forming the Patty

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Simple moral of the story? When forming large (6 ounce or larger) patties for the grill or the broiler, form the patties wider than you'd like them to be, and create a small dimple in the center by pressing down with your fingers. If you plan on pan-frying a burger, there's no need to take this step.

Also, be honest with yourself about your weight and wear your belt at an appropriate girth. I, for instance, know for a fact that I'm as slim, trim, and dapper as I ever was before I started cooking a few dozen burgers a week. It's the darn scale that lies.

Also, my belt shrinks.

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Continue here for the recipe for Juicy Broiled Burgers »

About the author: After graduating from MIT, J. Kenji Lopez-Alt spent many years as a chef, recipe developer, writer, and editor in Boston. He now lives in New York with his wife, where he runs a private chef business, KA Cuisine, and co-writes the blog GoodEater.org about sustainable food enjoyment.

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