Some folks balk at the idea of putting American cheese anywhere near their burger. "Cheese? You call that stuff cheese? More like orange chemical plasti-crap. No thanks!" they say, as they peel off the orange slices and fling them against the wall all angry-like.
On the other hand, as you may know from my past record, I'm a bona-fide, American Cheese-o-phile, and I'll defend it to the end. It's because nothing else melts like it. It envelopes a cheeseburger or a grilled cheese sandwich in a fatty, salty goo that drips and melts into every nook and cranny of a well-formed patty.
And therein lies the fundamental problem with American cheese: it melts perfectly, but tastes bland.
For a while now, chefs and cooks of the "molecular" variety have been trying to come up with a solution to this problem. Heston Blumenthal, of England's The Fat Duck, suggests emulsifying Comté cheese into a base of herb-infused sherry along with sodium citrate to keep it smooth, then pouring it out onto a silicone sheet, letting it set, and cutting it into squares. The first time I tried to make it, I didn't meet with much success, but have since been able to successfully pull it off. I've also had luck with the very similar cheese slices Nathan Myhrvold suggests in Modernist Cuisine, made with both Emmenthal and Comté emulsified into wheat ale. You end up with very tasty slices of cheese that melt almost as well as American cheese does.
Now these recipes are all well and good, but there's one problem: They're a pain in the butt to make. Burgers, almost by their very definition, are fast food. When I'm searing up a batch for lunch or dinner, I don't have the time or inclination to reduce sherry and wheat beer, emulsify cheese, measure out chemicals, pour and cool onto silicone sheets, then cut into slices before even starting on my burger itself.
What I want is a working method to get any cheese to melt smoothly like American cheese in the same amount of time that it takes my buns to toast and my burger to cook. Is that too much to ask?
A quick, but relevant diversion: This past Sunday morning, I was driving through central Connecticut on my way out to Cape Cod to do some "research" (i.e., eat the heck out of a boatload of fried seafood), and what better way to whet your appetite for fried clams than with a cheeseburger? I ended up stopping by Ted's Restaurant in Meriden, a working-class burger joint that's been churning out their specialty, steamed cheeseburgers, for over 50 years.
Now, I've never had a steamed cheeseburger before in my life, and after tasting one of Ted's—supposedly the best—I can tell you that I never really want to again. Sure the meat was beefy, moist, well seasoned, but it was, well, steamed. It tasted washed out, and with no browning, the best beef in the world fails to live up to its potential. There were other problems as well, most of which have been enumerated in Nick Solares' post on the subject, but I'm not here to rip into Ted's (there are plenty of people on both sides of this argument, and I don't want a war breaking out here).
I am here to tell you what is undeniably awesome about Ted's cheeseburger: the melted cheese.
Both the burgers and cheese get cooked in a custom-built steamer in little rectangular trays. As the steam envelopes the tray of young Vermont cheddar cheese, it heats it evenly, slowly melting it until it forms a gooey, lava-like substance that pours over the patty of beef, completely coating it. It's pretty awesome stuff, and a method I decided to immediately incorporate into my burger cooking arsenal.
Great story, right? But what's it got to do with the topic at hand? George Motz (author of Hamburger America) has one of these steamers and was kind enough to lend it to me for a bit of research. One of the things I immediately noticed when melting cheese in the steamer is that it melted far more evenly with a much lower likelihood of breaking and separating into greasy pools than any other method of cheese-melting I've encountered.
But as we soon discovered (apart from the fact that steamed cheese and seared burgers go great together) is that even with steaming, you still can't get certain cheeses to behave when melting. So what exactly makes a cheese break anyway?
On Moisture and Fat
Take a look at this lovely block of Comté. As we all know, it starts as milk: a mixture of water, proteins, fat, and a few trace minerals all swished together in a white, frothy soup that gets squirted out the nipples of cows (ain't that appetizing)? Now when cheesemakers convert this milk into cheese, they start by adding rennet, an enzyme found on the interior lining of calves' stomachs. This rennet causes proteins in the cheese (mainly casein) to unravel and link together into a matrix, which in turn traps both fat and liquid in its web.
After pressing out excess liquid, the cheese then gets aged, during which period, it loses yet more moisture through evaporation. The older a cheese is, the less moisture it has. The less moisture it has, the higher its concentration of fat, protein, and other minerals. Luckily, all that fat remains trapped away in its protein net, which keeps it from pooling out in greasy puddles when you warm it.
Melting changes all of this. As soon as you being to heat cheese, its fat begins to soften. Even at warm room temperature, you'll notice that cheese gets softer as it sits—this is all due to the softening of fat.
At higher temperatures—between 130°F and 180°F or so—proteins start losing their grip on each other. The net gets holes in it, and minuscule liquid fat droplets begin to escape. Just like fish finding their way out of a fisherman's net and schooling, as soon as these fat droplets are free they start to congregate and amass themselves into larger and larger pools. Eventually, you're left with a sticky, tangled ball of protein surrounded by a greasy pool of fat. Ick.
I'm sure you've all seen this happen when trying to melt an expensive slice of really well-aged cheddar on your burger.
Within a given class of cheeses, the age of a cheese has a direct relationship with the relative moisture content, which in turn has a direct relationship with how easily it melts. With low moisture cheeses, like, say, the 20-month old Comté above, proteins are more tightly packed together, and thus form tighter bonds which must be heated to a higher temperature to melt. At the same time, this high temperature heating causes extra moisture to evaporate. Without a good ratio of liquid to fat, it's simply impossible to form a smoothly flowing emulsion.
How Steam Helps
With traditional methods of melting cheese—in a pan, under the broiler, in the grill—it's very hard to transfer heat evenly and efficiently to the cheese. One part of the cheese inevitably ends up overheating before the other comes to melting temperature. This can exacerbate breaking, as localized hot pockets will form on, say, the base of the pan, or at the top of the cheese under a broiler. And once fat starts breaking out, it makes it even easier for more fat to break out.
A steamer fixes this problem in two ways. First, it heats very evenly. Inside a steamer, there are constantly shifting and flowing convection currents of hot air and water vapor traveling around. This forces energy all around the cheese, not just from the top or bottom surface like in a pan or broiler. Grating the cheese so that steam can flow easily around it helps on this front.
Secondly, and almost more importantly, steam also adds liquid to the cheese. Much of the heat that is transferred to the cheese comes from the energy released when water vapor condenses into actual droplets of water as the steam hits the cooler surface of the cheese. The water droplets coat the cheese, adding back some of the moisture that was lost during aging.
By the way—you don't need a magic custom steamer to do this—small bowls of cheese set in a standard steamer insert over a pot of simmering water will work just fine.
With younger cheeses like mozzarella, young cheddars, or Jack, steaming in itself is an effective way to melt your cheese without breaking it. For older cheeses, you need to still need to give'em a little helping hand.
So how does one form a stable emulsion? Two ways: fixing the ratio of liquid to fat, and adding an emulsifier. This is exactly the way that American cheese slices are formed. To make American cheese, curds of real cheese (yep, real, honest-to-goodness, cultured cheese!) are melted together along with extra milk and an emulsifying agent.
If you check the ingredients list with an open mind and a willingness to find out exactly what those long, funny-sounding chemicals really are, you'll find that they're completely harmless, and indeed occur naturally in many foods you eat every day. For instance, trialcium phosphate is actually a naturally occurring salt that you'll find in milk...and when you burn animal bones.
In commercial cheeses, these emulsifying agents generally work on a molecular level—they are tiny molecules with hydrophillic (water loving) heads and hydrophobic (water-hating, i.e., fat-loving) tails. These molecules bridge the gap between fat and water, allowing them to coexist relatively harmoniously.
But there are other types of emulsifiers out there. Flour, for instance, can help keep a mornay sauce from breaking. It does this by absorbing water in its starch, swelling up and gelatinizing, and physically impeding fat molecules from bumping into each other and coalescing, like a bouncer at a night club.
I tried tossing my cheese with a bit of regular flour as well as with some cornstarch before steaming it, but it didn't work all that well. The problem is that it takes too long for the flour to hydrate and gelatinize. By the time it's in a state in which it can perform its emulsifying duties, it's already too late—the fat has escaped. What I need is a way to get my flour to absorb water and gelatinize faster.
Luckily, there's a product on the shelves designed to do exactly that.
Gold Medal's Wondra flour is an instant flour—that's an ultra-low protein flour that's been pre-gelatinized, then dehydrated into individual, sandy granules. Because of this treatment, it doesn't have the same raw flavor as regular flour, and it very rapidly absorbs water, making it excellent at forming smooth, lump-free emulsions. Tossing my grated cheese with a bit of it before steaming helped quite a bit, though it still wasn't quite as smooth or break-free as I would have liked it to be.
I can't be sure without a microscope, but my instinct tells me that the problem is that as the cheese melts, even when coated with the Wondra flour, some of the fat leaks out before sufficient steam condenses on the surface to fully hydrate the flour. The solution? Just add more liquid.
By adding just a teaspoon of heavy cream or milk per ounce of grated cheese to my bowl. I was able to form a mixture that melted and stretched long, thin, gooey strands as you bit into it, yet was solid enough to stay put on top of a hot burger, just like a slice of good old American cheese.
While I admit that the applications of this method are pretty limited—cheeseburgers, grilled cheeses, and the like—and the texture is not quite as great as you'd get from a true-blue American cheese or chemically emulsified homemade cheese slice, there are some major advantages here.
For starters, you can make it with long-lasting pantry staples that you can purchase at any supermarket. It's also extremely fast. It takes about 30 seconds for you to set up a steamer and toss some grated cheese and flour together with cream, and an ounce of grated cheese (the right amount for a 4- to 6-ounce burger patty) set in a steamer insert takes just about a minute to melt into a gooey fondue-like consistency that sets as you pour it on top of your cooked burger.
Great flavor and perfect meltability? Who says we can't have our cake and eat it too?
And please—for the love of god—sear your patty, don't steam it!