How to Rescue Overproofed Dough

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It happens to the best of us. You wait many hours for your dough to proof so that you can bake it, and then, somehow, you forget about the dough (it’s easy to do, especially when you’re juggling meal prep during the holidays), and it overproofs. You may have even baked the overproofed dough, hoping it would magically return to life; instead, you end up with a pale, low-volume loaf that smells like stale alcohol. Overproofed dough, however, doesn’t have to meet its end in the bottom of a trash can. While working on Modernist Bread we developed a technique for saving overproofed bread.

The ultimate goal of proofing bread is to increase the volume of a shaped piece of dough through the production of carbon dioxide. Most of the carbon dioxide produced during fermentation happens in the final proofing stage. (The largest volume increase comes during baking when the dough nearly doubles in volume in the oven.) To expand, dough must be strong enough to retain the gas that it has produced. Gluten makes the dough elastic enough that it can expand around bubbles without tearing. Proofing, which begins once the dough is shaped and placed in a proofing vessel or on a flat surface, has some effect on flavor and texture, but it is key in determining the shape, volume, crust, and crumb of the bread.

When carbon dioxide exerts more pressure than a fully proofed dough can withstand, the cell membranes tear, releasing the gas and deflating the dough. An overproofed dough won’t expand much during baking, and neither will an underproofed one. Overproofed doughs collapse due to a weakened gluten structure and excessive gas production, while underproofed doughs do not yet have quite enough carbon dioxide production to expand the dough significantly.

Calling proof, knowing when the dough has reached its maximum expansion, is one of the more challenging things bakers have to learn to do. It takes practice and learning from a few mistakes. Conventional wisdom holds that overproofed doughs are irretrievably damaged and should be thrown away. Our experiments found just the opposite. In fact, we were able to resuscitate the same batch of dough up to 10 times before it suffered any serious loss in quality.

Our method for saving overproofed dough works for many kinds of dough, including French lean doughs, high-hydration doughs (you may see a slight decrease in volume as well as in crumb size for these), and country-style doughs. The method also works for farmers’ bread and most rye breads that contain a proportion of bread flour, such as landbrot; brioche and enriched doughs, including sandwich breads; and pizza doughs, though they may have a pale crust once the dough is baked.

Sourdoughs are more problematic; you should attempt to revive a sourdough only if it was made and proofed within a few hours. Sourdoughs that are cold-proofed overnight or longer acidify because of the presence of lactic acid bacteria. This acidification makes the dough very tough; as a result, if you degas and reshape it, the dough is overly tense, and still tough. You’ll end up with a loaf that doesn’t expand or bake well, and that is also misshapen and very sour. While some people (including us) like that biting flavor, others may find it too sour.

Mistakes are inevitable when it comes to proofing bread, but there’s no need to throw out dough if it proofs too long. Below is our step-by-step guide to saving overproofed dough (we call technique dough CPR).

Dough CPR

Step 1: Perform the fingertip test to make sure your dough is overproofed. The test involves gently pressing your finger into the surface of the dough for 2 seconds and then seeing how quickly it springs back. The dent you make will be permanent if the dough is overproofed.

Step 2: Remove the dough from the basket or other vessel in which you’re proofing it.

Step 3: Degas the dough by pressing down firmly on it. The pressure applied is the same as when you shape the dough.

Step 4: Shape the dough, and return it to the basket or other vessel for proofing.

Five Easy Tips For Freezing Your Sourdough Starter

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One of the most important discoveries we made while developing and refining the recipes in Modernist Bread is that yeast is among the most resilient life-forms we’ve ever encountered (and we encounter many in our lab, which we share with a bunch of biologists). As it turns out, freezing temperatures do not kill all the yeast and lactic acid bacteria in a preferment. Some die, but most remain dormant while frozen. The key is to know how to “wake it up” properly and to feed it well so it comes back strong and ready to leaven.

There are a lot of great reasons to try freezing your sourdough starter. Using a frozen preferment affords an almost instant starter; even with the added thawing and feeding time required, it provides a significant time savings over starting one from scratch. Having a preferment ready to go is convenient—you can freeze it in portions and just thaw what you need—and frees you from a feeding schedule. There’s no need to worry about entrusting someone with your starter when you go on vacation.

Our experiments demonstrated that a frozen levain will perform well for up to 2 weeks after freezing it. Eventually the ice crystals in the frozen preferment grow big enough to damage the yeasts and bacteria, rendering them useless for leavening. If you have levain that has been frozen for more than 2 weeks, you can still use it in combination with commercial yeast. The less-active levain will still provide your bread with complex flavor, and the yeast makes the dough rise.

Tips for Freezing Levain

Working with frozen levain is simple, although freezing your starter involves more than throwing it in a jar and stashing it in the freezer. Here are a few recommendations to help you get you started.

Tip 1: Freeze your preferment immediately after you make it. Freezing a ripe preferment won’t give the yeast the nutrients it needs because there will be little food left.

Tip 2: Our experiments demonstrated that a frozen levain will perform well for up to 2 weeks after freezing it. If you have levain that has been frozen for more than 2 weeks, you can still use it in combination with commercial yeast for an instant sourdough flavor. We utilize this technique for the Second-Chance Sourdough recipe in Modernist Bread.

Tip 3: Divide the preferment into whatever weight you would typically use for a specific dough. Stiff levain can be portioned directly into zip-top bags. You may want to add 10 g to the amount that you are freezing because ultimately some will stubbornly remain in the bag. Lay the bags flat on a sheet pan to freeze them.

Tip 4: For liquid levain, portion the preferment into an ice cube tray and use an offset spatula to even out the tops of the cubes. We use a piping bag to inject it deeply into the tray as possible, eliminating air pockets. Once it has frozen into cubes, remove them from the tray, and put them in a zip-top plastic bag in the freezer.

Tip 5: When you’re planning to make fresh bread with your levain, just thaw what you need. Take the portion out of the freezer about a day before you need it and let it thaw at room temperature (21 °C / 70 °F). When it’s ready, the bag will inflate as carbon dioxide bubbles form in the preferment. If you froze your starter into cubes, pull out however many cubes you need for your recipe, put them in a bowl, and cover them with plastic wrap. After making our dough, we like cold-proofing our levain in refrigeration for 24-36 hours to help develop the flavor.

Sourdough Science

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Baking is applied microbiology. That may seem like an odd way to look at it, but it’s only a modest exaggeration. All yeast-leavened breads owe their shapes and textures to the actions of microbes. The yeast used to create bread can be commercially derived (baker’s yeast), or it can be cultivated from the environment around us in the form of a levain (sourdough starter). There are many reasons to use this popular preferment. Levains produce breads that have a depth of flavor that commercial yeast-based breads don’t and are more forgiving thanks to the longer fermentation time. Starting a levain takes time, though, and when you create a preferment using microorganisms from the environment, you must maintain the culture.

A variety of myths and legends surround sourdough starters, and many of them date far back in the long history of yeast and bread. Before it was possible to observe fermentation through a microscope, no one could have imagined—much less explained—how dough could leaven itself, as if by divine intervention. We’ve come a long way since then, and useful information about the science of levain and sourdough breads abounds today. And that’s important, because having a basic understanding of how the microbes in levain behave can make working with this preferment more straightforward.

Getting Cultured: Yeast and Lactic Acid Bacteria

A levain is a preferment used to make sourdough bread, composed of a mix of water and flour that is fermented by lactic acid bacteria (LAB) and wild yeast. By themselves, the raw ingredients that go into a sourdough are essentially flavorless. The sweet-and-sour flavors we love in these breads are by-products of the microbes’ mutually beneficial fight to survive and grow in a complex microscopic ecosystem. And the makeup of that ecosystem evolves over hours or days of fermentation.

Unlike commercial baker’s yeast, which are strains of yeast within the species Saccharomyces cerevisiae, the yeasts in levain are varied, including not only S. cerevisiae but also a mix of other species, such as S. exiguus, Hanensula anomala, and Candida tropicalis. This particular mix of yeasts makes each levain unique flavor-wise—and most importantly, gives the dough rise.

While many people think that their sourdough starter is made up primarily of wild yeast, it is far outnumbered by the lactic acid bacteria in the culture— LAB outnumber yeast cells in a mature sourdough starter by roughly 100 to one. In fact, a levain isn’t stable without the lactic acid bacteria that symbiotically live with the wild yeast.

Like yeast, many kinds of bacteria also engage in fermentation. Smaller than yeasts, most of these bacteria are members of the genus Lactobacillus, so named because the 200-odd species in this group produce lactic acid as they digest sugars. The fermentative power of an individual bacterium is far less than that of a yeast cell, which contains about 20 times the volume of a lactic acid bacterium such as Lactobacillus brevis. San Francisco–style sourdough bread, as well as many other sourdoughs from around the world, derives its characteristic tangy flavor from L. sanfranciscensis. Bacterial species from the genera Leuconostoc, Pediococcus, Enterococcus, Streptococcus, Weissella, and Lactococcus are also common in levain.

Yeasts and LAB coexist so well because each can grow alongside the other and tolerate, to a certain extent, the other’s defense mechanisms. Lactic acid bacteria, like yeasts, are greedy when it comes to resources. The two work together to poison their surroundings—the toxic cocktail they create is full of alcohol and acids that are made during fermentation. It’s a less than warm welcome for other microbes.

Lactic acid bacteria aren’t much inhibited by the ethanol that the yeasts give off. In fact, some strains of lactobacilli are more tolerant of ethanol than yeasts are. The LAB, meanwhile, secrete acids—notably, lactic acid and acetic acid—that lower the pH of the levain. (Scientists who have compared the pH of commercial yeast-based breads and sourdough breads have found that the pH of sourdoughs is much lower: 3.8 to 4.6 versus 5.3 to 5.8 typical of commercial yeast-bread breads.)

But the wild yeast species in levain are able to survive in the increasingly acidic mixture. Without each other, pure cultures of yeasts and LAB can be invaded by other microbes, and if left unchecked, both yeasts and LAB will produce more alcohol and acid than even they can tolerate.

When it comes to peaceful coexistence, it helps that sourdough yeasts and LAB like different foods. Yeasts are better able to make use of a wide range of sugars and starches. C. milleri and other yeasts are happiest eating glucose and fructose (and sucrose, which enzymes quickly break down into these two simpler sugars). L. sanfranciscensis and other LAB, in contrast, prefer maltose. Another display of teamwork is that yeast cells also produce amylase, an enzyme that splits the complex starches and polysaccharides in flour into sugars that are more digestible to the yeasts and their bacterial neighbors.

The Evolution of a Levain

When bakers create levain, they exploit one of the principal forces of evolution— natural selection—as they shape a microbial ecosystem into a tightly controlled tool for bread making. The process illuminates the remarkable ability of yeasts and LAB to adapt to specific environmental conditions.

The growth of yeast and bacteria depend on three key factors: availability of nutrients, acidity, and temperature. Because growth can happen exceptionally fast, species and strains that aren’t adapted to a specific diet (like flour) can quickly be overwhelmed and die out. This is precisely why the inoculants, such as raisin water, that some bakers use to jump-start their levain don’t make a difference. (We think flour, which is chock-full of microbes, and water work just fine.)

Additional factors, including hydration, also influence how a sourdough starter matures. Levain can vary in hydration. If you mix together equal parts water and flour, you’ll produce a levain that is fluid—that is, highly hydrated. We refer to this as a liquid levain (pictured on the right in the image below). If you add more flour to the mixture, say 120% flour to 100% water, the result will be stiff (left). In our experiments, we noticed perceptible differences in pH: the more liquid the starter, the more acidic it will be. (So if you like your sourdoughs good and sour, use a liquid levain.) Your culture can also be affected by contamination or invasion by dust particles, spores, and the like, which can introduce new microbes

Many bakers swear by their particular starter too. But from a microbiology standpoint, the makeup of a starter will be very different if the feeding schedule or temperature is inconsistent. If you aren’t careful, your special starter may be very different on day 1 than it is on day 20 (or even day 2). And different starters can create surprises, which isn’t a good thing if you’re trying to make consistent loaves.

A long-lived levain is almost certainly going to change in composition over time. Think of it like a city; a great city may be just as grand two centuries from now as it is today, but it will have different inhabitants—including some who are descended from the current residents and some who moved in later. A starter’s composition will stay the same only in a perfectly maintained sterile environment, more like a laboratory setting than a bakery. The community of microorganisms will fluctuate and adjust to whatever foods they are given and whatever living conditions they experience. If one strain finds the environment more welcoming than the others, it will quickly grow and crowd its neighbors.

But locking in a specific population of bacteria is not important. What matters is creating a hearty colony of yeasts and lactic acid bacteria that behaves predictably; in other words, as long as the levain is fed on the same schedule and kept at about the same temperature and hydration, it will ripen and mature as expected.

Why Does Baking Bread Smell So Good?

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Here’s a fun thing to try: stand outside a bakery on an early summer morning, and watch how people react to the smell of baking bread wafting out the door as they walk by. Their heads turn, their noses lift, their eyes close . . . It’s only a matter of time until someone says, “Oh my God—that smells good!”

What is it about the aroma of bread in the oven that is so irresistible? Yes, for many people, the odors evoke powerful, pleasant memories of childhood. But even people who grew up on plastic-wrapped, essentially aroma-free Wonder Bread break into contented smiles when they enter a bakery while the ovens are going. The reason has as much to do with chemistry as it does with psychology.

We can get some clues as to where the aromas originate by considering wheat products that don’t smell quite as good. Wheat pasta, for example, has essentially no odor when boiled, and not much even when baked—that heartwarming aroma from a baked lasagna comes mainly from the sauce, cheese, and meat, not the noodles. Most unleavened crackers don’t do much for the nose, either.

But chemically leavened baked goods such as biscuits and muffins (made with baking soda and baking powder rather than yeast) can smell very tempting once they start to brown. The color change is a sure tip-off that Maillard reactions are happening. These reactions—in which sugars combine with amino acids to form tasty golden and umber complexes— throw off lots of volatile aromatic compounds that float through the kitchen air and into your nostrils.

Recipes for biscuits and muffins almost always call for added sugar of some kind: the lactose in buttermilk, the fructose in fruit, the dextrose in corn, or even crystals of sucrose sprinkled into the mix. Added sugars help kick-start Maillard reactions.

Another, even better way to generate pleasant aromatic compounds such as ethyl esters (ethyl acetate, hexanoate, and octanoate) is to leaven the flour with yeast. As a by-product of the microbes’ metabolic processes, the yeast cells produce chemicals that break down during baking into delicious-smelling aromatics. The longer the fermentation, the more pronounced the yeast flavors become since the microbes have more time to produce these compounds.

We have tried baking the same bread recipe with and without yeast, and the yeast bread develops a far more complex flavor profile. A big part of the difference is how much better yeast bread smells. The unleavened bread also doesn’t brown nearly as well. Thanks to yeast, your dough is stocked with amino acids that are an integral component of Maillard and other browning reactions.

So the next time you have a loaf in the oven and your kitchen smells like heaven, you have the tiny yeasts to thank.

Is Fresh Yeast Best?

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Yeast—living, single-celled fungi—is one of the main reasons bread is so complex and special. These microbes behave like miniscule factories that specialize in the production of bubbles and booze by way of a process called fermentation. In addition to leavening dough, fermentation makes important contributions to the aroma, flavor, and texture of bread.

The yeast used to create bread can be commercially derived, or it can be cultivated from the environment around us in the form of a levain. Using a levain is considered to be the very definition of fermentation by some bakers who dismiss commercial yeast (also known as baker’s yeast) as not producing “real” fermentation. We reject that view; fermentation is fermentation, whether it involves levains or commercial yeast. One method is not more legitimate than the other. The fermentation method you choose depends heavily on your schedule, ability to plan ahead, and yeast preference.

Commercial Yeast

When it comes to commercial yeast, there’s an ongoing debate as to which type of yeast is best for baking bread: active dry, instant, or fresh. The main issue doesn’t seem to be about the “power” of the yeast but rather an unspoken stigma that persists for each kind. You might have heard that “fresh is best,” but in truth, yeast is yeast is yeast—Saccharomyces cerevisiae to be specific.

S. cerevisiae is a fermentation superstar—the species is used by bakers, brewers, and vinters, although the strains that they work with differ. Strains are often isolated, grown, and stored in tightly controlled conditions so that they are best adapted for particular situations, such as making a sourdough, a French bread, an ale, or a champagne. That means that you probably won’t get great results if you try to make bread using a strain developed for brewing beer or winemaking.

At this point you might still be wondering what type of commercial baker’s yeast you should use. If a baker uses the right techniques, there is no reason to use fresh yeast over instant yeast—in a lineup of baked loaves, you’d be hard-pressed to distinguish one from the other in terms of the yeast used. We like working with instant yeast rather than fresh yeast or active dry yeast. After you read our explanations of the differences between the three forms, you will be better equipped to make your own choices.

Fresh Yeast

Developed in the mid-19th century, fresh yeast is the oldest commercial form of yeast. It was originally sold as a cream of yeast mixed with a mash, which served as a growth medium. Fresh yeast is more commonly sold today in blocks of cake or compressed yeast that resemble crumbly, cream-colored modeling clay. Fresh yeast must be dissolved into a liquid but easily does so, dispersing efficiently throughout the dough, which is a plus.

Each gram of compressed yeast contains roughly six billion active yeast cells. Fresh yeast has the highest moisture content of any form of baker’s yeast, but also the shortest shelf life. Blocks require refrigeration and last for only 2–3 weeks after opening. Fresh yeast is highly perishable, a considerable drawback that can cause issues in bakeries as well as home kitchens. At the bakeshop, fresh yeast is likely to sit on the bakers’ worktable for hours while they mix many doughs. The warmth of the bakery will activate the yeast, and it will eventually die because it has nothing to eat. The home baker who buys a pound of fresh yeast must bake frequently to use it all up before it dies. The challenges that come with fresh yeast eventually sparked the next wave of yeast innovation: dried yeast.

Active Dry Yeast

Dried yeast was developed during the Second World War by Fleischmann Laboratories so that United States field infantrymen could bake fresh bread in their camps. The new active dry yeast was not as perishable as fresh yeast and therefore did not require refrigeration and had a longer shelf-life.

Dried yeast is an inert substance when you purchase it, but it becomes a living, thriving colony of microorganisms with the addition of some water and food. During the production process, water is removed from the yeast cells, reducing the moisture content from around 82% to 8% in the case of active dry yeast. The desiccation sends the cells into a state of dormancy. Particles of dormant yeast are coated with a protective layer of dead yeast cells to form tiny granules, which are then packaged for sale. Unlike fresh yeast, unopened packages of dormant, active dry yeast can be frozen for months.

Active dry yeast is more convenient than fresh yeast, but it still requires some additional work and comes with its own set of drawbacks. The dormant cells must be reactivated before use, which can be done by stirring the granules in lukewarm (40–43 °C / 104–109 °F) water. Active dry yeast is temperature sensitive—water that is too hot or too cold can damage or kill the cells, reducing the fermentation power of the yeast.

Around 25% of the yeast cells are killed during the production process, which means that active yeast has, ironically, the lowest amount of active yeast (by weight) of either fresh or dry varieties. Thus, more of it must be added to a recipe than other types of yeast. Dead yeast cells also leach a self-produced chemical called glutathione that relaxes dough. Small quantities of glutathione can be beneficial, depending on the dough, but it can quickly make dough become so relaxed that it’s difficult to handle. Active dry yeast is slower to ferment than both instant and fresh yeast. It needs to proof longer to achieve the same results as the other forms of commercial yeast; the time required will depend on the environment and amount of yeast in the dough. Still, smaller quantities of active dry yeast are often the only option available at supermarkets, which is likely why it’s still commonly used in home baking.

Instant Yeast

Instant yeast, also called quick yeast, was developed in the 1970s by French manufacturer Lesaffre. Like active dry yeast, instant yeast is sold as desiccated granules; it is even drier than active yeast, having a moisture content of just 5% or so. The difference is that instant yeast ferments faster, does not require activation, and is less sensitive to water temperature.

So why do we prefer instant yeast over all other forms of commercial yeast? For starters, instant yeast is truly instant—it does not need to be activated; although we prefer to bloom it, you can add it directly to your dough—and, as soon as it comes into contact with moisture, it will begin the fermentation process.

Instant yeast is made with a fast-acting strain of S. cerevisiae, and the noodle-shaped granules are finer than those of active dry yeast. The surface layer of dead cells is more porous than that of active dry yeast, which allows the granules to rehydrate more rapidly. During production, instant yeast is quick-dried, a process that produces significantly more living yeast cells. As a result its leavening power more closely resembles that of fresh yeast. Manufacturers add salts of fatty acids to the yeast to control rehydration and boost the yeast’s gassing power. The moisture content is lower, which increases the shelf life to 2 years in its vacuum pouch, or even longer when refrigerated. Once the package is opened and exposed to oxygen, instant yeast remains active for 1 year if it’s refrigerated after being opened—it’s the trade-off of the more porous surface. Compared with the active dry form, the instant variety produces more gas during fermentation.

Instant yeast is also available in a number of forms; the one you choose will depend on the type of dough you make. For example, enriched doughs with larger proportions of sugar require osmotolerant yeast; osmotolerant instant yeast requires less water than the instant yeast used in lean doughs. So instant yeast offers options you don’t have with active dry yeast, along with added convenience.

You’re likely to encounter an occasional bump in the road in the road when your local grocery store or purveyor only has one type of yeast on hand. Accidents happen and it’s all too easy to get the wrong package of yeast in a rush. Fortunately, this is one bread-making problem that’s easy to fix. By giving the yeast proper care and employing some basic math, you can use any form of yeast successfully. You’ll find our own conversion table on page 10 (volume 3) of Modernist Bread.

Visit modernistbread.com to learn more about yeast and bread-making.

Bake Fresh Flatbread On Your Grill This Summer

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It’s no secret that our team loves to fire up the grill—so much so that we even found ways to bake fresh bread with one while working on Modernist Bread. Gas and charcoal grills (and infrared grills, which aren’t common but can also be used for this purpose) aren’t the first option that comes to mind for baking bread. It turns out, however, that you can successfully bake breads and flatbreads on grills. Summer is the perfect time to expand your grilling repertoire by giving it a try. Read on to learn how to bake fresh naan on your grill in a few easy steps.

Naan is flatbread with a long history and a lot of fans. The soft flatbread is traditionally eaten in South Asia and often accompanies a meal. There are many varieties of naan—some are stuffed with meat or vegetables, others are filled with fruit or nuits, and some are topped with ingredients in much the way pizzas are. Naan is baked in a tandoor oven, which requires you to build up as much intense, concentrated heat as possible inside the oven’s cavity. The oven is well insulated and made of dense materials that absorb and retain heat for extended periods of time. This type of oven has been around for centuries and is meant to cook food quickly—slight charring is even expected because the oven is so hot.

Fortunately, it’s relatively easy to mimic a tandoor with a grill. All you need is a basic home grill, a baking stone or steel, and some really hot embers. You can cook more than one piece of dough at a time if you can fit it on the baking stone or baking steel. The dough cooks so quickly that you can cook it as needed and eat the bread warm.

How to Bake Flatbreads on your Grill

Step 1: Light the charcoal. Allow it to heat until it is burning as hot embers.

Step 2: Place a tava directly on the grill, and heat it, with the grill lid closed, to a least 290 °C / 550 °F, about 30 minutes. A tava baking dome is made expressly for baking flatbreads. Alternatively, you can use a baking stone, baking steel, or wok (make sure that it has a metal handle). The wok or tava can be placed on the grill facing up or down. Use an infrared surface thermometer directly on the baking surface to determine the temperature. If you don’t have this type of thermometer, make sure to preheat for the recommended time. While you can use the thermometer built into most grill lids, those only measure the temperature of the air directly in contact with the thermometer probe.

Step 3: Once the baking surface has reached the target temperature, carefully place the dough on the tava, wok, baking steel, or baking stone. You do not need to cover the grill again. Bake the naan until it has brown pockmarks and the dough itself has turned a creamy white.

Step 4: Flip the naan over. Once it has browned on the bottom side, remove it from the grill.

Step 5: Repeat the process with as many pieces of dough as you have.

Bread Is Lighter Than Whipped Cream

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The headline above is surprising but true, and you can test it yourself: put 1 L of whipped cream on the left pan of a balance scale and a 1 L brioche on the right. The scale will tip to the left. Whipped cream has a reputation for being light and airy, but it’s about twice as dense as brioche.

The demonstration is hard to believe because it violates our expectation that a foam should be lighter than a solid. But bread is also a foam—it is just a set foam. The brioche’s crust is solid enough, but the crumb inside is mostly air.

This simple experiment illustrates that the density of bread—that is, its mass divided by its volume—is less than that of almost any other kind of food. Ciabatta, baguette, brioche, sandwich bread, and other common yeast breads typically have a density of just 0.22–0.27 g/cm3. Whipped cream, by comparison, has a density of 0.49 g/cm3. A liter of whipped cream thus weighs twice as much as a brioche of equal volume.

Bread seems denser than it is in large part because its mass is not evenly distributed: a crunchy baguette crust, which resists cutting and chewing, is 50%–100% more dense than the crumb. The crust is about as dense as pinewood (and whipped cream), whereas the density of the crumb is more like that of cork.

But if the crust is as dense as whipped cream, why does crust feel heavier? The short answer is that the chemistry of these two foams differs. To bite through bread (a set foam), you have to tear apart strong chemical bonds among adjacent molecules. But to eat whipped cream (a colloidal foam), you merely have to push adjacent particles apart.

Intuitively, you might expect that airier breads, such as a baguette, are less dense than loaves that have a tighter crumb, such as pumpernickel and other rye breads. And, in fact, that’s true, as this chart shows.

As it turns out, brick-like rye breads are more dense than red pine—and less dense a kernel of wheat. Scientific insights like this are why we find bread endlessly fascinating and fun.

Gluten: How Does It Work?

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Gluten has gotten a bad rap lately—it was practically a four-letter word when we started working on Modernist Bread—but in the world of bread, it’s your friend. As Jimmy Kimmel discovered, there’s a bit of confusion about what gluten is and what it does. Whether you avoid gluten or can’t get enough of it, we think it’s important to understand how it works.

Gluten is a protein found in wheat products. In bread making, it’s exceedingly important. Think of gluten as the miraculous net that holds bread together; it helps dough rise by trapping gas bubbles during fermentation and gives bread its unique texture. Although bread begins with many of the same ingredients as cookies, pastries, cakes, and even shortbreads, it has a completely different consistency. Gluten makes bread airy and satisfyingly chewy—it’s hard to imagine enjoying a chewy cake or a bread that crumbles like a cookie.

Gluten is formed when two of wheat’s native proteins, glutenin and gliadin, come into contact with water. That’s why it’s more accurate to talk about the gluten potential of a particular flour, rather than its gluten content. Either way you phrase it, the more gluten a flour can produce, the more able the dough is to hold gas bubbles, and those gas bubbles are what gives bread an open crumb.

Adding water to flour starts a chemical process that can eventually lead to gluten development. When we grind wheat flour, we destroy the structure of the seed (the cells and organelles), preventing germination. But a cascade of chemical reactions will still occur when the flour is hydrated because the materials that cause the reactions are still present. Gluten development occurs when we add water to flour and let the enzymes work as they were intended.

Gluten Development

From a baker’s perspective, gluten development begins during mixing. The basic point of mixing is to hydrate flour. Mixing matters not because it is necessary to develop gluten; you can develop gluten with minimal mixing (there really is no need to knead). Mixing is essential because it speeds up the hydration process and ensures that water is evenly dispersed throughout the flour.

When hydrated, the glutenin and gliadin proteins almost immediately bind and form gluten. The longer glutenin pieces link up with each other via disulfide bonds to form strong, stretchy units of molecules. These interlinked strands are among the largest protein molecules yet identified. More compact gliadin proteins allow the dough to flow like a fluid, whereas glutenins contribute strength.

Although hydration happens quickly, it takes time to form the chemical attachments that knit gluten proteins together into a strong network. Proteases (protein-snipping enzymes) begin cutting strands of gluten into smaller pieces that are able to make additional connections. Protease is found in very small amounts in wheat flour; an excess of it would cut gluten strands too much and have the opposite effect on the gluten network.

As mixing continues and the ingredients transform into dough, the chains of proteins become more numerous and elongated; they organize into a sort of webbing (the network can be seen in the image above, which was taken with a scanning electron microscope) that has both elasticity (the ability to stretch) and extensibility (the ability to hold a shape). Without this little protein tango, bread would be a very different thing: flatter, crumblier, denser, and less chewy.

The network of gluten will continue to develop, gradually becoming stronger and more complex, up until the dough is fully proofed. Enzymes have even more time to act while the dough rests and begins to ferment. Chains of gluten grow longer and stronger as more and more molecules stick together. During bulk fermentation, bakers periodically fold the resting dough to help align the gluten strands into an even, organized structure, which gives the dough the integrity it needs to expand as the carbon dioxide produced by the yeast and water vapor are introduced into the bubbles.

When the gluten network is strong enough, the dough can be shaped. Bakers check gluten development by performing the windowpane test, which involves stretching a portion of dough in your hands. A well-developed dough can be stretched so thin that it’s translucent. Gluten strands tighten and reorganize once again as the dough is divided and shaped. The tension created during shaping helps the dough expand at a steady rate, producing uniform loaves.

Most of the carbon dioxide production during fermentation happens in the final proofing stage. The largest volume increase comes during baking when the dough nearly doubles in volume in the oven. To expand during both processes, the dough must be strong enough to retain the gas that’s produced. Gluten makes the dough elastic enough that the bubble walls can expand like a little balloon without tearing up until the point where the bread overproofs. When carbon dioxide exerts more pressure than a proofed dough can withstand, the gluten structure weakens, releasing the gas and deflating the overproofed dough.

Other Factors

There are other factors that influence gluten development, such as the type of flour you use. Generally, bread bakers are shooting for an 11%–13% protein level, which will give good volume and texture to a loaf. Protein content varies among flours, and in most cases the higher the protein content, the more gluten the dough can typically form. This doesn’t mean that one flour is better than another; rather, different types of flour are better suited for different purposes. We use lower-gluten flour when we want to make cake, for example, because it won’t form a gluten network that can make a cake’s texture rubbery.

Some wheat varieties, including semolina and most ancient grains, don’t have good gluten-forming properties, which is why they are often blended with other wheat flours in bread recipes. Whole-grain wheat flours contain plenty of protein, as well as bran and germ, which chemically and physically affect the strength of dough. The thirsty particles prevent proteins from fully hydrating, excrete compounds that weaken gluten, and can create microscopic holes in the wall.

Other grains, including rice and corn, can’t form the gluten protein at all, although they do contain other proteins. Rye is a special case. It has some gluten, but not the kind that creates a network that makes for a light and airy bread. Rye becomes bread largely by means of pentosans. These polysaccharide molecules form a sticky gel when mixed with water. That gel—not gluten—is what gives breads with a high percentage of rye their structure.

The quantity of water present also plays into the gluten-forming process. Adding too little water won’t work; the flour must be sufficiently hydrated to activate the proteins that form gluten. Too much water also causes problems, resulting in more of a batter than a dough, in which a gluten network will form but never produce a cohesive mass.

Salt provides more than flavor—it strengthens gluten bonding. Although the gluten proteins naturally repel one another, the chloride ions in salt help them overcome that repulsion and stick together. You can see this change happen within dough when you add salt later in the mixing process: as the salt mixes in and dissolves, the tacky dough firms up.

Fats, such as butter and oils, slow down the gluten-forming process by coating the protein strands, which is one reason enriched doughs such as brioche call for longer mixing times. The coating acts like a barrier that prevents gluten proteins from sticking to one another, stunting the growth of long chains. It’s because of these clipped strands of gluten that we can intricately shape enriched doughs, such as challah. With a small addition of solid fat (1%–3%), lean dough becomes stretchier (allowing it to rise higher) and easier to handle. Fat-enriched recipes, like brioche, can call for large amounts of fat. Fat in these quantities hinder gluten formation and lead to a soft, tender crumb that is more like that of a cake.

Certain inclusions can have the same weakening effect. Any inclusion that contains lots of gluten-killing enzymes, for example, is generally tough on dough. That includes raw papaya (rich in papain) and pineapple (high in bromelain). A workaround is to cook these ingredients first; high heat destroys the enzymes.

Time serves as a general tool for controlling gluten development; the longer the flour and water spend together during the hydration process, the more numerous the gluten bonds will be, while a longer mixing time will speed up hydration by forcing the water into the flour. Time also allows enzymes to assist in gluten development, and most notably extensibility.

Mixing methods also matter. Hand-mixing techniques won’t hydrate the dough—and develop the gluten—as fast as machines. Using an electric mixer can make many breads feasible that would otherwise be difficult to mix by hand, like challah.

The next time you make bread, keep these factors in mind. If you want a taste of Modernist Bread, give our Chocolate and Cherry Sourdough, Portuguese Sweet Bread, and Pork Cheek Hum Bao recipes a try.

The Story Behind the Photo: Bread Pitt

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Every photograph tells a story, but there’s also a story behind every photograph: the equipment, the techniques, the location, and the time that went into composing the shot. There are over 5,600 photos in Modernist Bread and nearly half a million more were taken—that’s a lot of stories to tell.

Visual imagery is a huge part of what we do, but we faced new challenges with Modernist Bread. The bright, bold color palette from our previous books shifted to shades of brown and off-white when our focus turned to bread. That meant that Nathan and the photography team had to be even more creative with the visuals, which makes for a lot of great stories. While we can’t share them all, the story behind our all-bread Giuseppe Arcimboldo tribute (internally known as Bread Pitt) is one that we’ve been looking forward to revealing.

The Inspiration

In addition to historical texts, Nathan and the team looked to historical artwork to learn how bread was shaped, served, sold, and eaten over the centuries. Visiting museums like the Louvre and archeological sites like Pompeii, they found clues in art: ancient frescos of markets, mosaics of bakeries, depictions of the last supper, still-life paintings of food and meals. Along the way, some of those works also became the inspiration for photographs in the book.

The 16th-century Italian painter Giuseppe Arcimboldo is best known for painting chimerical portraits and caricatures composed entirely of objects. Some of his “composite faces” were made up of household items, such as books, gilded vases, silverware, tools—even a spinning wheel. But like many artists of his time, the natural world and its curiosities was a source of inspiration for Arcimboldo. He captured the likeness of subjects from a wide variety of flora, fauna, and foods. From a distance, Arcimboldo’s paintings appear to be ordinary portraits. Luckily, they can’t be taken at face value. As you get closer to the paintings, the objects reveal themselves and his subjects transform into surreal faces carefully made up of tree branches, flowers, roots, grains, vegetables, fruits, sea creatures, snails, birds—not to mention roasts.

Building Bread Pitt

Bread Pitt began as a sketch. In addition to being an inspiration, Arcimboldo’s work helped us figure out we could arrange different breads to create our own composite face. After studying the paintings, head chef Migoya began to map out the breads that he could use to make a face, which proved to be one of the biggest challenges of the project. Making the bread, instead of painting it, presented a special set of considerations. Taking shape, size, and proportion into account, he had to creatively fit different types of loaves together like puzzle pieces.

All the breads, for example, had to keep the proportions of a face. Mini-breads, which might lose their shape, were out and the scale of the face became apparent. Its nose, a full-size baguette, put into context how big all the other loaves had to be. The sketch itself had to be as true to size as possible so that he could also determine how many loaves to make.

Facial feature by facial feature, the details of our bread face started to come together. We used almost every shape of bread possible: challah as impeccably groomed hair, bushy eyebrows made of epi baguettes, pretzels for ears, miches became full cheeks. He included a number of French regional breads, thanks to their inventive shapes. A pain d’Aix, for example, resembles a bow tie and a fendu could easily double as lips.
Then the baking began. Over a couple of days he and the culinary team baked over five dozen loaves of bread. During that time, chef Migoya sculpted a base out of a large piece of Styrofoam that he reinforced with wire netting. Once all the bread was ready, he began building the sculpture, using metal rods and glue to keep the bread in place. From start to finish, construction took between six and seven hours.

When complete, the finished sculpture came in at over 3-by-4 feet. Nathan photographed the portrait of Bread Pitt in our photo studio. From the lighting to the dark painted backdrop, the set was carefully built to mimic details found in many of Arcimboldo’s works.

Epilogue

After the shoot, Bread Pitt was moved to our library with other mementos we accumulated while working on Modernist Bread. The sculpture stayed intact for about six months—much to our surprise and delight. But like all things, Bread Pitt couldn’t last forever. Although Bread Pitt eventually became buggy and fell apart, he is immortalized in photographs, the book, and the sketch that still hangs in our kitchen.

Upcoming Modernist Bread Events

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The release of Modernist Bread is just a couple of months away—you’ll find it in bookstores starting November 7. To celebrate, coauthors Nathan Myhrvold and Francisco Migoya are hitting the road this fall to give audiences a preview of their book before it goes on sale. Join us at any of the events below to hear new insights and discoveries from Modernist Bread as well as the story behind what is sure to be the biggest, most comprehensive book about bread. Tickets are on sale now.

September 2017

Thursday, September 28 at 7:00 p.m., Toronto

Royal Canadian Institute and George Brown College Talk

In Conversation with Nathan Myhrvold: The Future of Bread

Event location: George Brown College

Tickets and information

October 2017

Monday, October 2 at 7:00 p.m.,  Boston

Harvard Science and Cooking Public Lecture Series

Insights from Modernist Bread with Nathan Myhrvold

Event location: Harvard University

Tickets and information

 

Wednesday, October 4 at 7:00 p.m., Brooklyn

A special event for members of Heritage Radio Network and MOFAD

Modernist BreadCrumbs Live: Nathan Myhrvold in Conversation with Michael Harlan Turkell 

Event location: MOFAD

Tickets and information

 

Saturday, October 7 at 10:00 a.m., New York City

The New Yorker Festival

Nathan Myhrvold Talks with Michael Specter

Event location: Gramercy Theatre

Tickets and information

 

Thursday, October 19, Chicago

Read It & Eat Author Talk

Insights from Modernist Bread with Co-Author and Head Chef Francisco Migoya

Event location: Read It & Eat

Tickets and information

 

Monday, October 23, Brooklyn

StarChefs 12th annual International Chefs Congress

Modernist Bread demo with Francisco Migoya

Event location: Brooklyn Expo Center

Tickets and information

 

Thursday, October 26 at 7:30 p.m., Seattle

Town Hall Seattle

Modernist Bread with Nathan Myhrvold

Event location: SIFF Cinema Egyptian Theater

Tickets and information

 

We have more appearances in the works—follow us on Facebook, Twitter, and Instagram for event announcements, updates, coverage, and more.