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The Food Lab: The Science of No-Knead Dough
I'm telling you right off the bat here, that as far as personal innovation goes in this article, there's not all that much. All I'm doing here is taking someone else's brilliant idea and breaking it down for you a bit, offering a few suggestions and other applications.
That said, I've never seen what I consider to be a really satisfactory explanation of the science behind the No-Knead Bread recipe,* so I'm gonna try and fill that hole here. And what cool science it is.
*Addendum: In a completely inexcusable bout of absentmindedness, I completely forgot to mention the excellent chapter on No-Knead bread in Aki and Alex of Ideas In Food's book. Those guys have got science to spare, and if you haven't read it yet, it's worth more than a thumb through!
In 2006, Mark Bittman introduced the world to a recipe from Jim Lahey of Sullivan Street Bakery, which had a whole bunch of home cooks opening up their Dutch ovens and exclaiming oh my goodness—I can't believe I just did that! It certainly had me thinking that.
The No-Knead Bread recipe became an instant hit, and, I'd be willing to wager, started off an entire generation of home bakers on an entirely new journey.
Here's how the recipe works: combine flour, yeast, and salt in a bowl. Add water and stir with a spoon. Allow to sit overnight. Shape into loaf and allow to rise. Bake in a preheated Dutch oven.
What emerges from the Dutch oven is a crisp, crackly, deeply colored loaf of bread with a crust that snaps and pops as it cools. Slice into the bread and you see the open, airy, wildly bubbly crumb of the best artisanal bakeries with a tender, chewy texture. Nearly perfect bread, in other words.
Now, there are those (including myself) who'd criticize the flavor. The original recipe was under-seasoned (as Lahey himself has even admitted), and with its short, warm fermentation period, it doesn't develop the rich, complex, malty flavors of a truly great loaf. But these are minor quibbles in what is otherwise a completely revolutionary recipe.
Even more interesting to me than that it works is how it works, because by understanding the how, we can then modify the recipe to fit many different baking situations, even improving its flavor.
But before we get there, let's take a quick look at the awesome science behind this equally awesome recipe.
While the no-knead part of the no-knead dough recipe certainly has some cool action going on, at least for home bread bakers (and we'll get to it soon), the real important innovation here is baking the bread in a Dutch oven, and it works in two ways: by increasing the radiant energy heating the bread, and by increasing the humidity of the baking environment. (For those of you who don't know what a Dutch oven is, it's a thick-gauge, large pot with a heavy, relatively tight fitting lid.)
You see, a ball of dough isn't the homogeneous blob that it appears to be. It's in fact a very complex network of bubbles of carbon dioxide gas both large and small produced as living yeast consume sugars. These bubbles are separated separated by thin, stretchy, flexible sheets of gluten (that's the network of proteins that provide structure to good bread).
How does a ball of raw dough go from being small and dense to large, light, and airy? Through a phenomenon known as oven spring.
When that dough first enters a hot oven, both the carbon dioxide gas inside those bubbles as well as some of the water vapor trapped in them begin to expand due to the increase in heat. This expansion causes the stretchy bubbles to inflate—for a little while. Eventually, the proteins in that make up the gluten will coagulate and set, preventing the dough from expanding any more. The trick to airy bread is to get those bubbles to increase in size as rapidly as possible, giving them plenty of volume before the proteins have time to set.
This is accomplished by transferring as much energy as possible as fast as possible to the dough. And that's where the Dutch oven comes in.
Most folks tend to get inordinately obsessed with temperatures. I can get my oven up to 600°F, or the floor of that wood fired pizza oven gets to 800°F! In reality, it's not temperature that matters, but energy, and the transfer thereof. Indeed, if temperature were the only thing that mattered when it comes to how fast something gets cooked, then we'd be able to stick our hand into a 212°F pot of boiling water just as easily as we could reach into a 212°F oven, and we know that that's not the case, right?
What I'm getting at is this. Place your Dutch oven inside a 500°F oven and give it an hour or so to heat up. Now, the air inside that Dutch oven is going to be at or around 500°F. There's no way for it to get hotter, because unless you are providing some sort of external energy source, there's no way for an object to get hotter than its surroundings. Basic thermodynamics here.
However, place something inside that 500°F Dutch oven, and you'll transfer energy to it far faster than you would if you placed that same something on the shelf of your full-sized oven. Why? One word: radiation.
See, the thick cast iron (or stainless steel, or ceramic, or whatever your Dutch oven is made of) sides of a Dutch oven can hold onto a massive amount of heat energy, and that energy is constantly being emitted in the form of electro-magnetic radiation.* The walls of your regular oven do the exact same thing. However, because a Dutch oven is so much smaller, and because radiant energy decays over distance, objects inside the small, enclosed space of a Dutch oven absorb much more energy through radiation than an object sitting in the center of a large oven.
*Mostly in the infrared range
Think of it this way: you are the loaf of bread, and the walls of the oven is a circle of kids in storm trooper costumes, ready to barrage you with a hailstorm of foam missiles shot at low velocity out of Nerf-N-Strike Alpha Trooper guns. In a normal oven, these storm troopers are pretty far away—say, 100 feet. They'll shoot at you with all they've got, but only a relatively small number of their darts will actually make contact. You get mildly annoyed.
Now take that same scenario, but change their striking distance to a mere 10 feet. Same number of kids with guns (that is, same temperature), but this time, many many more of them are actually gonna be able to hit you. You get screaming mad, blowing up just like a balloon. All make sense now?
On top of all that, there's another factor involved: humidity.
Professional bakers often use steam-injected ovens in order to increase the humidity of the baking environment. This is because moist air transfers heat much more efficiently than dry air, once again increasing the rate of transfer of energy between the oven and the loaf of bread. Moisture also causes starches on the surface of the dough to gelatinize, a key step in producing the microscopic bubbles and bumps that add crunch and texture to your bread, like this:
So that covers the baking method, and truth be told, it's a method that works no matter how you make your original dough. Now we can look at the actual "no-knead" part of the no-knead bread recipe.
When you first hear it, it sounds impossible. From experience, I know that in order to produce great bread, I need to knead the dough until it forms a significant amount of gluten, right?
Well let's take a look at the dough on a microscopic level and see what's really going on.
Flour is composed mainly of two things: starch, and proteins. Of these proteins, two of them glutenin and gliadin are the most important. They're the guys who get together to form gluten.
In their normal state, the long, kinky proteins (no, not in that way) are tangled up with themselves, like a knotted fishing line. Your goal is to untangle the proteins, tie them together into a longer line, then use those lines to weave a net, which can be used to trap carbon dioxide produced by yeast. This is what kneading accomplishes.
By gently rubbing the proteins against each other, you stretch them out and cause them to line up and cross-link. With enough kneading, you eventually form them into sheets of gluten.
So how does the no-knead bread recipe, which, appropriately, has no kneading involved produce the same effect? With the help of enzymes. Flour naturally contains enzymes that break down long proteins into shorter ones in a process called autolysis (auto meaning "self" and lysis meaning "break down"). Bakers have known about this process for years, and many incorporate an autolysis step into their recipes, mixing together flour and water and allowing it to rest before adding the remaining ingredients and kneading (salt can inhibit the action of autolysis).
By breaking down the proteins into shorter pieces in this way, they become much easier to untangle and re-align, greatly increasing the efficiency of kneading.
The No-Knead Bread recipe simply takes this concept to the extreme. By mixing together your ingredients and letting them sit around at room temperature for a long, long time (at least 12 hours, and up to 24—remember, there's salt in the dough which inhibits autolysis, so you need to compensate for this), the proteins are broken down so much, that even the tiniest of mechanical actions can cause them to align and link up.
Huh? But I thought this was no knead dough, not "tiniest amount of kneading" dough.
Yes, indeed it is, and truth be told, there is some kneading going on, but it's not being done by you, nor any other human or even by a member of the kingdom Animalia, for that matter. It's the yeast..
Let's take a quick look through a time lapse series of photos of the dough as it sits overnight.
0 Hours: dough is still lumpy. Gluten formation is minimal.
4 Hours: Enzymatic action has broken down some proteins, causing the dough to slacken and spread.
8 Hours: Yeast has produced quite a bit of carbon dioxide. As these bubbles slowly grow, their stretching causes proteins around their edges to align with each other.
12 Hours: Slowly but surely, the bubbles moving through the dough, effectively forming the same gluten that would be formed by manual labor.
16 Hours: The yeast have completed their task, both leavening and kneading the dough for you. Thanks guys!
What you're left with is a slack, easy-to-work dough that stretches beautifully, and bakes up with excellent gluten structure and massive bubble formation. Since no-knead doughs require a large amount of hydration (usually water has to make up at least 70% of the weight of the flour, as opposed to, say, white bread which is closer to 60% or a baguette, which is more like 65%), they can be a little challenging for first time bakers to work with. They stretch easily, practically pouring out of their rising vessel.
My advice is to use plenty of flour, and practice, practice, practice!
Problems and Applications
The main complaint I had with the original No-Knead Dough recipe is not the technique or texture of the final product—it's the flavor. First off, it's way undersalted (which, again, Lahey admitted after the original recipe ran), presumably to keep the salt from inhibiting autolysis too much. I've made no-knead bread with up to 2% salt with no problem, so I can only chalk it up to a misprint or an error. My normal rate is 1 1/2% salt.
But worse than that is the background flavor of the bread itself.
Yeast produces different byproducts depending on the temperature it ferments at. So dough formed with a warm ferment ends up with a sour, yeasty off-flavor, as opposed to the richer, maltier aromas you get from bread fermented at cooler temperatures. As I've shown before, giving lean doughs like this a stay in the fridge for three to five days can massively increase its flavor and its performance. Same goes for the no-knead bread.
After allowing it to rise at room temperature overnight, I'll stick mine directly into the refrigerator for three days. There's another advantage built into this as well: cold dough is much easier to handle. Gluten gets stiffer as it cools, which means that refrigerated dough will be much simpler to shape into a ball or a long loaf, or whatever shape you wish to bake it in.
After shaping, cover is with a bowl or a flour-coated kitchen towel and let it rise at room temperature for a couple of hours to take the chill off it and leaven for the final time before slashing it with a sharp knife (this allows it to expand faster in the Dutch oven, and makes it look pretty), and baking.
How do you know your bread is done when you bake it? Same way you know your meat is done: with a thermometer. As bread bakes, water is both evaporated and bound into the structure of the crumb. This occurs pretty much in correlation with the internal temperature of your bread. Once it reaches around 209 to 210°F, not much else is going to happen except for a bit of burning, so yank it out and let it rest.
If you want to make your life even easier, get yourself a good gram scale to allow you to easily calculate ingredients without having to dirty up measuring spoons, cups, or bowls. Using a scale and a metal bowl, you can make bread and end up with only a single bowl to wash!
Here's the basic method I use:
To 100 parts flour, add 1.5 parts salt and 1 part instant yeast. Whisk those together. Add 70 parts water, and stir to combine. Cover, then let rise overnight. Transfer to the fridge, let ferment for three days, then turn dough out on to a well-floured surface. Shape dough, sprinkle with flour, and cover with a floured cloth. Let it rise for at least two hours and up to 4 at room temperature. Slah, then bake in a preheated 450°F Dutch Oven for 15 minutes with the lid on. Remove the lid, and continue baking until it hits around 209°F, 30 minutes or so. Let it cool.
The greatest part about no-knead dough is that you aren't limited to one type of bread. The same method can work for rustic loaves, boules, baguettes, and yes, even pizza dough.
I made this pizza here using the exact same dough that I used to bake the bread above. See how nicely it browns after its three day cold ferment?
I tried baking pizzas using a sort of modified version of the Dutch oven technique (I preheated a Dutch oven upside-down in a hot oven, lifted the base off, placed the pizza directly on the overturned lid, then covered it with the base again), but it wasn't nearly as successful as the already pretty great (if I do say so myself) skillet-broiler method, so I stuck with that.
Check out this awesome hole structure in the crust:
Now if that ain't one beautiful pie, I don't know what is.