The Anatomy of Flour
A wheat berry, or wheat kernel, has three parts: the bran or exterior, the endosperm, or most of the interior, and the germ, a small section of the interior. The bran accounts for fiber and nutrients, while the endosperm accounts for starch and protein. The germ is the wheat seed, and it is high in fats and vitamins. Flour is wheat berries which have been refined, ground into a powder, and sometimes “enriched” or imbued with more nutrients. Different types of wheat have distinct protein contents—bread flour and 00 flour contain lots of protein, while cake and pastry flours contain little protein. Plain white flour only contains the endosperm, or starch portion of wheat—this is why it appears white. Whole wheat flour, on the other hand, contains the endosperm. Semolina is simply coarse flour, which is why it appears more yellow.
Gluten
Think of a balloon. When you blow more air into the tiny, hollow piece of rubber, it expands massively in volume. Gluten is an amazing substance, because of its innate ability to link with other gluten molecules and form a tight bond. Wheat flours contain two principal proteins, glutenin and gliadin, which combine to form gluten in the presence of water. Glutenin are long protein threads which build the strength of gluten, and gliadins are smaller proteins which allow the flexibility of gluten. The combination of strength and flexibility is what enables bread to rise.
When bread is kneaded, the gluten strands are flattened out and aligned to form long strands. The result of kneading is a complex network, held together by millions of microscopic chains. When yeast and bacteria produce carbon dioxide (see Part 2), the gas particles remain trapped within the gluten network, and when bread is placed in a hot oven, the gas and water molecules speed up and bounce around the glutenous cavities, forcing the bread to expand upwards and outwards. Eventually, the starches in the bread gel, and the gluten network is set in place.
If the dough is not kneaded enough, it means the gluten strands are not sufficiently aligned. The dough will lack strength, and when the bread enters the oven, high-speed gas particles will rupture gluten chains, deflating the loaf. On the other hand, if bread ferments too long and the yeast and bacteria produce too much carbon dioxide, even properly aligned gluten strands will not be able to contain the sheer amount of gas bouncing around. The gluten chains will snap, and the bread will collapse.
A simple way to tell if the gluten network in bread is strong enough is by performing “the windowpane test.” To perform the test, stretch a ping-pong ball-sized chunk of dough out with your fingers. If there is proper gluten development, the dough should be able to stretch thin enough that you can see light and movement behind the web of dough.
A demonstration of the windowpane test
Time and Temperature
A helpful way to visualize gluten is as a muscle. After exercising, your muscles might feel tense or sore. When repeatedly worked, gluten tenses up and becomes more difficult to work with. Athletes use ice baths to ease muscle pain and reduce tension—similarly, gluten relaxes in cold environments.
Especially with high-gluten breads, rests at room temperature or the fridge make shaping much more manageable. Bagels are some of the most glutenous breads made; in my recipe, the dough has several rests in the fridge between stages of rolling and twisting. Without rests, the dough springs back as soon as it is rolled—making shaping almost impossible.
Gelatinization
To understand how dough turns into bread in the oven, you first need to understand the structure of starches. The starches found in flour vary in size and shape but are usually chains of glucose and other sugars. The starches have a crystalline structure, meaning the molecules are uniformly arranged.
Gelatinization is the chemical reaction in which starch absorbs water, thickens, and sets. When starches and water are heated to high temperatures, the crystalline structures break apart as starch molecules bind with water molecules. Starch molecules absorb more water and swell up—eventually they burst, releasing amylose sugars and water. The water, amylose, and starch form a solid network strengthened by gluten. If you have ever added cornstarch to a sauce, or made a roux, you have harnessed gelatinization.
In certain bread recipes, including bagels and pretzels, dough is boiled in an alkaline solution before baking. This process quickly gels the crust so that when it bakes, it turns glossy, crackly, and crispy. Since hydrogen ions break up starch bonds, starches gel faster in alkaline solutions (solutions with fewer hydrogen ions).
Salt
Salt is an overlooked, but essential ingredient to breads. Beyond its practical use (to add flavor), salt has unique chemical properties which enhance gluten’s strength. Upon adding salt, the chloride ions break the bonds between gluten and starches, and bind gluten together; the reaction is noticeable, as the dough tenses up upon salt addition. Acid, which contains lots of hydrogen ions, has a similar effect on starch molecules.
Salt, however, can also be the enemy of yeast and helpful enzymes. If you recall back to chemistry class, you may remember that osmosis is the process by which water moves from zones of low solute concentration to zones of high solute concentration. When salt is added to dough, water exits yeast cells to maintain osmotic balance—resulting in a slower fermentation. Salt also kills proteases, the incredibly helpful enzymes which help shorten gluten strands (and form a structurally sound loaf). The autolyse is done without salt so that starches and yeast have a chance to absorb water, and proteases have a chance to act before being inhibited.
I hope I’ve made it clear that I adore flaky sea salt. Flaky salt elevates most foods; it adds texture and flavor contrast to sweet pastries, like babka and cinnamon rolls, and helps bring out yeasty, earthy flavors atop sourdough. Trust me: the next time you bake cookies, a small sprinkle of Maldon will make all the difference.
Bread with butter and salt—what more could I ask for?
Fat
In the baking world, enriched breads are treasured for their buttery, rich flavor and unique texture. Though it adds richness and flavor, fat also acts as a tenderizer, as it inhibits gluten development. When introduced to bread dough, fat molecules coat gluten, preventing them from forming connections. Some enriched breads require much more kneading—in other recipes, fat is introduced to dough only after it has formed a strong gluten network.
The most common types of fat added to breads are egg yolks, butter, milk, and vegetable oils. Of all these, egg yolks impart the most flavor (and color) to breads, but each oil has its own benefit. Butter is the most common fat in bread, but especially in savory breads, olive oil adds a more nuanced, earthy flavor. For plain loaves, professional bakers may use vegetable oil or shortening, and vegan bakers embrace fats such as coconut oil and alternative milks.
Pastries such as croissants, as well as biscuits and pie crusts, achieve their flakiness through a process called lamination. Typically, laminated bread is made by encasing a block of butter within dough, rolling the dough out, folding it over itself, and repeating. The result is a dough with several dozen layers. In the oven, the water within butter turns into steam and pushes the dough upward, while the fat melts into the bread. Bakers sometimes describe the structure of a croissant as “a honeycomb,” as the dough turns into a thin membrane surrounding air pockets.
In brioche, a very fatty bread, I prefer a stronger network of gluten which can support the weight of the butter. However, other recipes (such as challah) are characteristically supple. In developing my enriched bread recipes, I looked for a balance between texture and flavor. Trust me, I never skimp on the butter.
Easier Lamination
Though croissants are the classic example of bread lamination, they're tricky to pull off (and test!) in a home kitchen. To demonstrate the effects of lamination, you can try something much simpler: pie dough. The only non-bread recipe on my website is for a galette with rhubarb and raspberries, perfect for summer snacking.
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