Know your Dough

a rough-draft excerpt from Breaducation

As I mentioned last week, I handed in a much-too-long draft of the front matter for Breaducation to my editors recently. Given its excessiveness, it’s highly likely that it won’t remain in this form once it makes it into print. And given the amount of work I have yet to do in the next four months to get it finished, I thought I would share some sections from it here, as something of a sneak preview for you all and a reprieve for me. This excerpt, from the chapters on bulk fermentation, is all about dough dynamics, the sorts of things that bakers think about and strive to manipulate when working with doughs.

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Dough dynamics is the term I use to cover all of the variables that go into and effects that appear in a bread dough—all the sorts of things that bakers consider when creating a dough, and observe and tweak when working with one. This all might seem overwhelming at first, especially since most of these elements occur in tandem with the others as a web of interrelated effects. Manipulating any one of them will have an effect on other elements too—pluck one string and the entire web vibrates in response.

This also makes it challenging to write about dough dynamics in a linear way, since each element is defined by its relation to the others—it's all hard to describe without leaning on at least a few tautologies. If all this doesn't make sense to you at first, hopefully it will by the end, or at least after a few read-throughs. (For a much deeper dive into these concepts, particularly those related to dough rheology, I highly recommend Trevor Wilson's excellent e-book, Open Crumb Mastery, which inspired and informed it.)

Dough rheology

Many of these ideas relate to rheology, which is the branch of physics concerned with of the "flow" of matter, particularly gases and fluids. Doughs are solids, but they behave like fluids in many ways. Water in a dough exists in two forms: bound and free. Bound water is locked up within the dough's materials—its starches, proteins, and fiber. Provided each of these elements is saturated with water, any additional water in the dough will be free. It is free water that allows a dough to flow—the more free water, the more the dough behaves like a liquid. Bread baking in many ways is about manipulating and controlling flow—we want to encourage a dough to be as liquid as necessary to achieve a certain result, but not so much that it cannot hold itself up or we cannot coax it into a particular shape.

Dough development and structure

Dough development is the creation of structure in a dough during kneading, proofing, and shaping. Gluten development is a major part of dough development, but it also involves additional elements, including the production of gases during fermentation—which expands the dough—the production of acids during fermentation, and the manipulation of structure by the baker—the guiding of both the internal and external structure of the dough into a particular arrangement.

Structure is the result of dough development in all of its aspects—the form of the bread inside and out: the overall shape of the bread and the size, shape, and distribution of the alveoli within it.

Hydration and dough wetness

Hydration is the amount of water relative to flour. This obviously influences the texture of a dough, since one with more water will flow more than one with less. While bakers (me included) often relate the hydration of a dough to its texture, hydration is really only an indirect indicator of texture. Two otherwise-identical doughs made from different flours will likely need different amounts of water to achieve a similar texture, for example. So it's better to think about dough texture in terms of wetness or dryness, independent of hydration—wet doughs flow freely, while dry ones do not.

How much a particular dough flows depends much upon the absorption rate of the flour. Refined flours are less absorptive than high-extraction or whole-grain ones (since the bran in whole-grain flours absorbs far more water than the starches), and will need less water to achieve a particular texture.

Even two flours of a similar extraction rate can behave differently to one another. Those with higher protein generally need more water than those with less to flow in a similar way, both because the proteins absorb more water than the starches, and because more gluten usually means more strength, and the stronger the dough, the less apt it is to flow.

How a flour is milled can have an effect on flow too. The milling process and the hardness of the grain determines the amount of damaged starch that is produced during milling. (Despite the name, "damaged" isn't necessarily a bad thing here: some amount of damaged starch is inevitable, and it plays essential roles in baking: Starch damage makes the sugars in the starches accessible for fermentation; without some amount of damaged starch, a dough will ferment sluggishly, if at all.) Damaged starch absorbs two to three times as much water as undamaged starch, so the more damaged starch, the more water the flour will absorb.

The hydration of a dough isn’t always a constant throughout the process; it can be manipulated along the way to make adjustments or to achieve a certain effect. A baker might simply hold back some water from a dough at first, adding some or all of the remainder once it is clear it can handle it. Or they might employ a bassinage during mixing, in order to develop structure in a dough before all of the water is incorporated.

Elasticity and extensibility

Elasticity and extensibility are two ends of a single dough-flow spectrum. An elastic dough resists flow or manipulation, while an extensible one flows freely, either on its own, or when manipulated by a baker. Much of the effort in bread baking is directed toward achieving the proper balance between extensibility and elasticity in a dough, in order to achieve a dough that flows just so—one not so elastic that it is hard to shape—bakers call these doughs “bucky”—while not so extensible that it runs off the bench or collapses after shaping (or “slack”). This delicate dance happens throughout the bread baking process: in the initial choice of flours and hydration, the inclusion of a preferment or not (and the selection of preferment type), mixing method and degree, folding, degree of fermentation, shaping technique, and more.

The “proper" balance between elasticity and extensibility of course varies from bread to bread. Doughs that require lots of manipulation—baguettes for example, which require extensive folding and elongation, or hand-stretched flatbread doughs—benefit from more extensibility, to avoid a dough that fights back against the baker or springs back after shaping. Other doughs want more elasticity, either to make shaping easier—it's challenging to form a perfect bagel or cinnamon roll if the dough spreads without any effort on the part of the baker—or to give the shaped bread sufficient structure to hold itself up during proofing or baking.

More water—up to a point—promotes extensibility in a dough; reducing hydration promotes elasticity. If a dough fights being folded or shaped, perhaps it needs more water; if it spreads out rapidly after folding or shaping, it might benefit from a slightly lower hydration.

Another way to manipulate extensibility is in the selection of flour: doughs higher in gluten-forming proteins will—all else being equal—be more elastic, those lower in them more extensible. But the ratio of the two proteins that combine to make gluten in the flour—glutenin and gliadin—matters too. Glutenin gives doughs elasticity and strength, while gliadin provides extensibility and flow. In wheat flour, the ratio of glutenin and gliadin is relatively balanced. Spelt flour is much higher in gliadin than wheat flour, so adding spelt to a formula can yield a more extensible dough. (And using too much of it can produce doughs that are slack, making them challenging to shape and low in volume once baked, unless a baker makes other adjustments to the process or formula.)

Strength and weakness

Two other terms commonly used to describe a dough’s flow are strength and weakness, each of which are related directly to elasticity and extensibility. A strong (elastic) dough resists natural flow and manipulation by a baker; a weak (extensible) one flows freely and is easily manipulated. It's important to keep in mind that in bread baking these terms are entirely neutral: a strong dough is not better than a weak one, nor is a weak one worse than a strong one. As with elasticity and extensibility, the aim is a balance between strength and weakness, and where you set that balance depends upon what sort of dough (and bread) you want.

So why use these terms at all? Well, for one thing, they are used often, so it's worth knowing what someone means when they do. Moreover, dough strength is not set in stone from the start, it is something that can increase (or decrease) over the lifetime of a dough.

Tension

Another term bakers use in reference to dough strength is tension. Put simply, tension is elasticity plus force: A rubber band at rest is elastic, but floppy and flexible; stretch it out widely between your hands and it can be plucked like a guitar string, because it is tense. Ditto for doughs—manipulation during folding and shaping creates tension. Dough tension can be ephemeral or permanent; the tension created by folds done early on in the bulk fermentation or spaced far apart fades, while those done closer together or later on will produce lasting tension. An experienced baker learns to create and work with tension: knowing when to apply more force or folds when the dough demands it, and when to apply less force, minimal handling, or longer rests when tension is adequate or becoming excessive.

During preshaping and final shaping, a loaf has both external and internal tension. The “skin” of the loaf is like a bag around the dough; by manipulating the tension in the skin, a baker can often coax even a loose, less-than-structured mass of dough into a smooth, stable shape. Stitching—cross-linking the skin of the loaf across its seam—is one form of dough tensioning during shaping, as is rounding or cloaking, in which the baker uses the friction of the loaf against the bench to tighten the skin. The internal tension of a loaf is created by the strength and structure within the dough.

A bag of balloons

In Open Crumb Mastery, Trevor Wilson likens bread dough to a “bag full of balloons,” a perfect metaphor for how a dough behaves at any point during its lifetime. Imagine each alveolus in the dough as a balloon; when the dough is first mixed, the balloons are present, but un-inflated. (A dough’s alveoli are formed during mixing, not fermentation; they begin as micro-bubbles invisible to the eye when air is first incorporated into the dough.) As a result, the bag is floppy and flexible; the dough is easily stretched out, and it flows freely within its container. It can be folded and shaped easily, but the shape is transient, because there’s nothing holding the alveoli up internally.

As gases begin to accumulate, the alveoli-balloons expand; the larger they are, the less able they are to slip and slide past one another. Early on, the alveoli are only partially inflated, so they remain relatively flexible. The dough remains easy to stretch, fold, and shape, but the result of that effort is more permanent.

Eventually, the alveoli-balloons become inflated to capacity, and the dough is full and rigid. The gluten surrounding the alveoli is taut and inflexible, so the dough resists elongation and manipulation. And the alveoli are unable to move around within the dough; their positions are fixed in place.

The two main ways bakers manipulate doughs after mixing are folds during the bulk fermentation and preshaping and shaping at the end of it. When each of these actions take place dictates both its effectiveness and effect. Folds performed early on are transient; they do reorganize the gluten network internally, but the macrostructure of the dough quickly returns to its original, amorphous state.

This transience does not mean you can skip folding a dough early in its lifespan; folding also arranges gluten webs into a more-ordered structure, preparing the dough for expansion. And it serves to even out the temperature of the dough, moving the inside outside and vice versa. It does mean you can be a little more relaxed about when and how often you do the folds early on, however.

Folds performed once the dough has begun to expand are more permanent. The dough still tends to relax and spread during the interval between each fold, but more slowly. The dough starts to have shape and hold itself upright in the container. If the baker returns to perform the next fold before the effects of the previous one have subsided, structure within the dough will accumulate.

Once the dough has expanded maximally, folds become challenging to perform, at least without severely degassing the dough. The taut, swollen dough resists stretching out, and is likely to tear if handled excessively. And any folds that can be done tend to unravel. For this reason, most bakers tend to cluster their folds during the early-to-middle phases of the bulk fermentation, so that the internal structure of the dough is set before the dough has fully expanded. After the folds are complete, the dough is then allowed to rest, to complete fermenting and relax somewhat before shaping.

Preshaping and shaping usually involves some amount of degassing, which partially “resets” the strength of the dough, making it more amenable to manipulation. But there is a limit to how much extensibility can be restored, so the choice of when to end the bulk fermentation and begin shaping dictates how much the dough can be coaxed into shape. Loaves shaped early on are easier to form into various shapes (provided the dough already has enough structure to retain the shape), while those shaped late into the bulk fermentation are challenging to shape without potentially degassing it excessively.

Fermentation rate: exponential, not linear

Remember, the growth rates of yeast and bacteria are exponential, not linear. Each cell divides into two; those two divide into four, four into eight, eight into sixteen, and so on. Which means that the rate of fermentation in a dough—and gas production—speeds up over time; in fact, most of the gas and acidity is produced during the latter stages of the proof. An experienced baker learns to anticipate this ramping up of fermentation when deciding when and how often to perform folds and when to shape the dough, knowing that some amount of structure will materialize in due time. (This is yet another reason to cluster folds to the early-to-middle phases of the bulk fermentation.)

Acidity

Since fermentation rate and gas accumulation increases over time, acidity does too. When dissolved in the water in the dough, carbon dioxide is acidic, so the pH of a dough drops (i.e., becomes more acidic) as fermentation progresses. When a dough is fermented with sourdough or is yeasted and long-fermented, lactic acid bacteria also contribute organic acids to the dough, lowering the pH further. Acids strengthen the bonds between gluten strands, so fermentation strengthens dough structure doubly: both from the force of the expanding alveoli on the dough and the accumulation of acids.

Each of these effects happens with or without the involvement of the baker with the dough. Folding is important for building the proper structure in a dough, but it isn't essential for structure formation generally. Over time a baker comes to trust this process, knowing that—even when a dough starts out wet and soupy—it will eventually strengthen and firm up on its own to a certain degree. The trick is learning to handle a dough enough to give the dough the guidance and tension it requires to form an ordered, well-shaped loaf, without overdoing it.

Enzymatic activity

The dough-strengthening effects of increased acidity are not limitless; as the pH drops, the activity of gluten-degrading protease enzymes picks up too. They reach peak activity around pH 4.0, and their activity ramps up quickly the closer the dough gets to this point. This is the primary reason that over-fermented doughs collapse rapidly during proofing or in the oven.

Doughs containing large quantities of whole-grain or high-extraction flour—with high percentages of enzyme-rich bran—have naturally higher enzyme loads. They also ferment more quickly, thanks to the extra enzymes and nutrition they supply, so a baker must take extra care when formulating these doughs and anticipate how they will behave as the fermentation progresses.

Preferments and the amount of prefermented flour

The addition of preferments—sourdough or yeasted—can increase or decrease dough strength depending upon a number of factors. Preferments bring structure to a dough because the gluten they contain is pre-developed; they also supply acidity, which further strengthens the final dough. Thus, the amount of preferment used in a dough has great implications for how the final dough behaves. When the preferment is sourdough, the amount used also dictates the rate at which the final dough ferments.

But preferments can also confer extensibility to a dough at the same time, particularly if they are high in hydration, since liquid levains and poolishes are rich in the yeast-degradation products L-cysteine and glutathione. So a baker learns to select one type of preferment or another, depending upon what they aim to achieve.

On open crumb

While much of this chapter has been informed by Trevor's book, Open Crumb Mastery, you'll note that I haven't actually referenced "open crumb" anywhere in it. I absolutely get the appeal of those pearlescent, wildly open-crumbed loaves on social media that so many bakers lust after—they are beautiful to behold—but it's never been something I have spent time chasing myself. Of course I want the crumb on my lean, rustic loaves to be open rather than dense, but they usually are without me needing to engineer it specifically. And in any case, most of the time I want my bread to be open enough, but not so open that whatever I slather my toast with ends up on my lap rather than my mouth. I achieve the style of crumb I like through careful fermentation of my doughs (and starter), creating sufficient structure in my doughs through proper mixing and folding, and deliberate, gentle shaping.

If super open-crumbed loaves is something you desire, I think that's great! I love all the many ways bread can be made, and I love learning about and considering the techniques that go into achieving certain results. But open crumb for open crumb's sake is not my thing, so you'll want to read Trevor's book if you do, along with my friend Addie Roberts's excellent Secrets of Open Crumb as well. Trevor and Addie are experts in open-crumb baking, and their books will provide much of the intel you need. In any case, as they undoubtedly would tell you as well, you'll need to master the basics before you can push the envelope, crumb-wise.