Sourdough is arguably the oldest form of leavened bread. The first loaves were sourdoughs, and levain was also the first leavening agent. Travel to bakeries and kitchens in any corner of the world, and you’ll likely find some form of sourdough bread. Sourdoughs are as diverse in flavor, texture, and volume as the cultures in which they’re made.
Throughout this blog, we refer to sourdough starter as levain. Why? We use “levain” to distinguish it from sourdough bread to avoid any confusion. In our books Modernist Bread and Modernist Bread at Home, “levain” means the starter, while “sourdough” refers to the bread itself. Here, we’ll discuss what makes levain different from simply using yeast or other types of preferments as well as the benefits that it can bring to bread.
The Difference Between Commercial Yeast and Preferments
Yeast can be incorporated into bread directly (a.k.a. direct dough), as a preferment (previously fermented dough), or as a combination of the two.
Fast and efficient, the direct dough method, which utilizes commercial yeast, takes as few as 3 hours from start to finish to bake a loaf of bread. When fermentation occurs that quickly, however, there is less time for flavor to develop.
Using a preferment involves either mixing a portion of water and flour together and inoculating it with commercial yeast or allowing wild yeast and bacteria to colonize it (called a levain, or sourdough starter); over a period of hours or days, fermentation gets underway. After the preferment “ripens,” you mix it into the dough. Because of the longer fermentation time, the use of a preferment will improve a bread’s flavor and texture; this is particularly the case when using levain, which gives sourdough its distinctive tang.
A combination method involves adding commercial yeast along with a preferment. Some bakers choose this method because the commercial yeast accelerates the fermentation time, while the preferment contributes flavor and accelerates hydration, which cuts down on mixing time.
Types of Preferments
Overall, a preferment is a portion of the dough made in advance, anywhere from 3 hours ahead to several days. Once mixed, the preferment is allowed to ripen at room temperature. When it is finally added to the dough, yeast activity is well underway (as is fermentation), and the portion of flour used in the preferment is fully hydrated.
There are several benefits to using a preferment. First, because the flour in the preferment is already hydrated, the preferment functions as a partially developed dough, which cuts down the overall mixing time. Preferments can also contribute flavor to the dough. The longer the period of time the yeast is given to feed and multiply, the more aromatic compounds are created as a by-product of fermentation.
We divide preferments into three categories:
- Those started with commercial yeast
- Those started with wild yeasts and bacteria, which we call levain (sourdough starter)
- A combination of commercial yeast and levain. Second Chance Levain is a combination of the two and one of the best shortcuts we’ve found in our bread-making research. Essentially, when you use an inactive levain in your dough, it will provide only flavor and some hydrated flour. It will not supply any leavening, so you must add instant yeast to the recipe. We teach you how to do this on page 52 of Modernist Bread at Home.
Types of Commercial Yeast–Based Preferments
Commercial yeast–based preferments mix flour, water, yeast, and sometimes other ingredients. They mature within 3 to 18 hours and are then incorporated into the bread dough, often with additional yeast. These preferments primarily aid in jump-starting hydration, reducing mixing time, and enhancing the final bread structure. Here are the main types:
Poolish—a high-hydration (equal parts flour and water) preferment commonly used in recipes due to its ease of use
- Pros: easy to mix and incorporate into dough; enhances flavor and texture
- Cons: requires precise timing to avoid over-fermentation
Biga—a drier version of poolish that is typically used in Italian breads
- Pros: adds a subtle flavor complexity
- Cons: stiffer and harder to mix; often requires an electric mixer
Sponge—made with flour, water, yeast, and enriched with eggs, butter, sugar, and/or milk; primarily used in enriched breads like brioche and challah
- Pros: ideal for enriched doughs; adds richness and tenderness
- Cons: can be difficult to mix evenly into dough; requires more effort
Then there is levain. Technically, levains are also a type of preferment, but they’re not started with commercial yeast. Given their popularity, we will spend the majority of this course discussing levains.
What Is a Levain?
Levain, the original preferment, gives sourdough its tangy flavor. Made from flour and water, it ferments naturally with wild yeast and lactic acid bacteria. The fermentation process varies depending on the method used for inoculation, resulting in a complex interplay of microorganisms that contribute to the unique taste and texture of sourdough. If you’re curious about the science behind this process, check out our blog for a deeper dive.
Learn more about sourdough science here.
The Benefits of Using a Levain
Using a levain to leaven bread has been a popular method for millennia. Despite the advent of commercial yeast, there are many compelling reasons to use a levain:
Depth of flavor: Breads made with levain have a depth of flavor that commercial yeast–based breads simply can’t match. Most commercial baker’s yeasts are made using a single strain of yeast within the species Saccharomyces cerevisiae,but the yeasts in levain are varied, making each unique flavor-wise. The lactic acid bacteria significantly affects flavor. The extended fermentation process develops complex, nuanced tastes that elevate the final product.
Flexible baking schedule: Levain-based breads ferment more slowly than those made with commercial yeast. This extended fermentation time offers more flexibility in your baking schedule. Sourdoughs are more forgiving, allowing for a broader window of time to bake the bread.
Reduced proofing time: Since some of the flour is already fermented before the dough is mixed, the overall proofing time can be shortened. This can be particularly advantageous when managing your time in the kitchen.
Cost-effective: Using a levain eliminates the need to purchase commercial yeast. While there are costs associated with feeding the levain, they are generally minimal compared to the ongoing cost of buying yeast.
Improved gluten structure: The natural acidity in a levain helps to reinforce the gluten structure of the bread. The lactic acid bacteria mix also strengthens the gluten network in the dough because the acids secreted by these bacteria strengthen those gluten bonds. This results in a better texture and a more robust loaf.
Extended shelf life: Levain slows down the staling process and inhibits mold growth. A loaf of bread made with levain can remain fresh, and even improve in flavor, for up to 3 days after baking.
The Drawbacks of Using a Levain
While there are many benefits to using a levain, there are also some drawbacks to be aware of:
Maintenance: Keeping a levain healthy requires regular feeding and care. This maintenance can be time-consuming and requires a level of commitment.
Inflexible quantities: You may end up with either too much or too little levain when you need it. This can be inconvenient, especially for last-minute baking.
Time-consuming preparation: Preparing a levain takes time. You can’t simply whip up a batch on a whim, which can be limiting for spontaneous bakers.
Tedious for infrequent bakers: For those who don’t bake regularly, the ongoing process of starting and feeding a levain can feel tedious. Some may find the effort to be burdensome after making a few loaves, even if those loaves are successful.
Space requirement: A levain needs a dedicated area in your kitchen to “live.” This can occupy valuable kitchen or workspace, which may be a concern for those with limited room.
Despite these challenges, we believe that creating your own levain is a worthwhile and rewarding endeavor.
FURTHER READING:
- Sourdough Science
- Second chance levain recipe—Modernist Bread at Home, p. 52
- How to make a poolish—Modernist Bread at Home, p. 44
- Preferments—Modernist Bread at Home, p. 42
- The cycles of yeast respiration and fermentation—Modernist Bread vol. 2:270
- Yeast storage conditions and shelf life—Modernist Bread vol. 2:277
- The evolution of a sourdough—Modernist Bread vol. 2:290–291
- The uses of other preferments such as a sponge or biga—Modernist Bread vol. 3:22–27
- Building an osmotolerant levain—Modernist Bread vol. 3:56
- The pregelatinization method (otherwise known as a yukone or tangzhong) in bread—Modernist Bread vol. 2:386
- Cooking with a yukone/tangzhong in Japanese Sandwich Bread—Modernist Bread at Home, p. 246