Natural yeast, in its many varieties, is pretty much everywhere—in the air, in the soil, in vegetation—and especially in carbohydrate-rich environments like the skins of fruits and the surface of grains. Natural yeasts lie dormant in flour. Commercial baker’s yeast, Saccharomyces cerevisiae, is a monoculture—a single strain of yeast cultivated commercially and sold in dried form or in moist cakes.
Prior to the use of commercial monoculture yeasts in the modern era, all leavened bread got its rise from naturally occurring yeast. These types of breads are now known as sourdough in the United States. This is how bread was leavened throughout most of its five thousand years of history.
The French word levain is derived from the Latin levare, meaning “to rise.” The words mother, chef, and levain all describe the same thing: a natural culture the baker uses as a leavening source. Some bakers and texts use different names for the culture at different stages; or they may use more than one culture. Chef often refers to a master culture that is fed separately, whereas starter refers to a portion of the chef that is fed in one or more stages and added to the final dough mix. I have always worked with a single culture that is fed and kept separately, taking some of that culture at a particular point of ripeness to leaven my final bread dough. I use the word levain to describe my culture at all of its stages, and that’s the word I use throughout this book. I use the English word leaven as a verb.
I avoid referring to my naturally leavened breads as sourdough because too many people associate sourdough with breads that are indeed sour in flavor and sometimes leave a sharp, vinegary aftertaste. In France, sour bread is probably considered a fermentation mistake, while in San Francisco, it’s a well-appreciated taste—although that may be changing. My preference is for complex flavors from the grain and fermentation that are subtle, in balance, and not sour.
A levain can support multiple strains of wild yeast, giving the baker an opportunity to create bread and other leavened baked goods with complex aromas and flavors. Such breads also have a more extended shelf life than breads made from commercial baker’s yeast. The yeast community in a levain culture consists of billions of rapidly reproducing, gas-belching, single-celled organisms. I like knowing that I can make them do what I want them to do.
Bakers feed their levain cultures anywhere from once a day to every few hours. In the following pages, I’ll show you how easy it is to start a new levain culture from scratch using just flour and water and following a once-a-day feeding schedule. Then I’ll explain how to feed an established levain, how to store it in the refrigerator if you won’t be baking with it every day, and how to restore it for its next use.
Baking with a levain culture is a fermentation craft similar in some ways to making wine from grapes and their naturally occurring yeasts: each manipulates fermentation to create an end product that meets a desired flavor profile and degree of complexity.
The character of a naturally leavened bread depends on a number of variables: how much water is in the culture, the temperature of the water used each time the culture is fed, the type of flour, the ratio of levain to new flour each time the culture is fed or refreshed, the feeding schedule, the temperature at which the levain is kept, how ripe the levain is, and how much of the levain is used in the final dough. The aroma, flavor, and appearance of levain breads and the consistency of the product from one day to the next are all expressions of the baker’s craft—his or her signature, in a sense. A true artisan baker is someone who understands how to manipulate the relatively small number of variables (which can yield an infinite number of possible results) to produce exactly the bread desired. In this book, I’ll give you specific instructions for making and using a natural levain culture my way, and then I’ll explain how to adjust the variables to suit your own tastes. Levain breads have the potential to be the most personal breads a baker makes.
The complexity of tastes in a levain bread arise from the community of wild yeasts and bacteria in the culture, fermentation gases, lactic and acetic acids, and, of course, time for these things to accumulate. My revelation “less yeast and more time” definitely applies here. Lengthening the fermentation time of levain doughs by retarding them at cooler temperatures greatly improves flavor. So does using smaller amounts of levain and allowing doughs to ferment for a very long time at room temperature. Bacterial fermentation and acidity add desirable tastes and aromas, but only if enough time is allowed for these very complex biochemical reactions to take place.
Acids are responsible for the sourness in sourdough. The vinegary taste comes largely from acetic acid. Lactic acids are common in milk, and indeed contribute a milky or buttery taste to breads. Both acids are often more evident as an aftertaste, unless the sour character is strong and pronounced. Many naturally leavened breads have a flavor profile that leans more toward one end of the acetic-lactic spectrum than the other. San Francisco sourdough is an excellent example of bread with strong acetic character—think “vinegary.” Levain cultures kept in cooler temperatures also lean toward the acetic end of the taste spectrum, as do stiffer levains. Bread made from a liquid levain, with equal parts flour and water (it has a soupy texture), has a distinctive flavor profile that leans toward the lactic acid end of the taste spectrum. Warmer levain cultures encourage lactic acid production, and just like the top-fermented ales that brewers ferment at warmer temperatures, these can produce fermented fruit flavors, especially when they get particularly ripe.
Want a little more detail? Here goes, with a shout-out to Teri Wadsworth and John Paul of Cameron Winery in Dundee, Oregon. The levain is a symbiotic culture of lactic acid bacteria and yeast. Lactic acid bacteria are a diverse group of bacteria that produce lactic acid, carbon dioxide, a small amount of ethanol, and other volatile flavor components as the end product of carbohydrate fermentation. Under the right conditions, lactic acid bacteria can also produce acetic acid. In a levain, the lactic acid bacteria feed mostly on the yeast’s metabolic by-products. As with natural yeast fermentation, time is required for the bacteria to grow and produce acids and other flavor components. Lactic acid bacteria are important in a plethora of fermented foods, including yogurt, beer, pickles, sauerkraut, and cheese, and the acidity they produce inhibits the growth of organisms that can cause spoilage.
I could go on about how alcohol can convert to acetic acid when there is an excess of fermentation, but I don’t want to distract from the main goal, which is to know how to manipulate the variables at play in the kitchen to make good levain bread. At the end of this chapter is a table, Variations in Levain Cultures, summarizing the variables and their impact on taste.
As a new levain culture is being established over the course of several days, it evolves in ways you can see, feel, and smell. At the beginning, right after you start it from scratch by mixing just flour and water, it resembles either bread dough or a batter, depending on how much water is used. Within 48 hours, after two daily feedings, the culture gets gassy, it increases to as much as four times the starting volume, you can see bubbles, and it has a weblike structure from its gluten. As the levain matures it develops a fragrant, sometimes pungent and alcoholic, acidic nose. We use some whole wheat flour in the levain at my bakery, and I call for doing the same in this book’s recipes. This results in a funky, leathery ethanol smell in the mature culture. That smell takes my mind to some undefined place, a place that makes me pause and where my eyes are open and not looking at anything at all.
A single hardworking yeast cell can divide, or bud, more than a dozen times. In the right environment, this replication, and that of all of the offspring, produces billions of yeast cells, each producing the gas that leavens and flavors the dough. Every time the levain is fed with flour and water, a new cycle of yeast replication and fermentation begins, and ultimately the entire dough mass is bubbling, lively with potential, and ready to be used to make more bread.
Much is sometimes made of specific sourdough cultures from a particular place or even preserved from a time past. For example, many people say you can only make a bread that tastes like San Francisco sourdough in San Francisco. Likewise, some people believe their levain is special because it’s been maintained for decades or it was derived from a special culture that someone gave them or that they ordered by mail. While there are minor populations of yeast and bacteria that are indigenous to specific geographic areas, the primary flora are the same in sourdoughs everywhere. It’s not a where-it’s-from game: it’s how it’s made, and with what ingredients, that makes the bread taste the way it does.
Many people believe their levain has a particular character due to how it was established; for example, with a bunch of grapes added to a mash of flour and water. I disagree. Grape yeasts live on grapes because that’s the environment that suits them. Grape yeasts don’t flourish in a flour environment. Again, it isn’t how a levain is started that determines its performance and flavor profile; what’s crucial is how it’s maintained. Natural selection will rule in the flour environment. The addition of grapes, apples, or other such ingredients to the starter provides sugars for fermentation and short-term aromatics. Malt would do the same thing: provide food to the yeast. Many of the microorganisms involved in starting a culture can’t tolerate the environment as the culture develops; only those that thrive in the environment that is developed and maintained will survive. As Raymond Calvel wrote in Le Goût du Pain, “Recipes for this purpose are often quite amusing, including cultures based on grape juice, potatoes, raisins, yogurt, honey, and so on.… I simply use the proper type of bread flour.”
Having said that, I have nothing against tossing some quality fruit into a mature levain culture for immediate use, and I know of one baker who uses honey in a special levain. My point here is to dispel the myth that a levain carries the elements of its genesis forward in its character. In fact, I’ve made some very interesting breads by adding fruit to the levain. At my bakery, we once made apple bread with a levain hydrated with apple cider. Best ever was when I grabbed a bucket of apple mash from Steve McCarthy at Clear Creek Distillery and added it to some of the bakery’s levain, which then went into a baba dough. That baba au pomme was one of the best things I’ve ever eaten.
In my naturally leavened breads, I aim for the middle of the lactic-acetic spectrum to produce bread with a mellow aroma and flavor that is satisfying by itself or can complement a variety of foods and wines. This kind of bread flatters whatever it is served with. It tastes great, it’s crusty and flavorful, and it’s the kind of bread I don’t tire of. I want to eat it every day.
The levain recipes in this book use 80 percent hydration for the levain culture. That means the water in the culture amounts to 80 percent of the flour, by weight. Levains can be more stiff, with hydration as low as 60 to 65 percent, in which case they will easily form into a ball. They can also be wetter—as much as 100 percent hydration. Really, a levain can be at any hydration, but the common range is between 60 and 100 percent hydration.
At my bakery, we use a levain with hydration close to that of the final dough it will be used in. I find this approach more balanced, as opposed to mixing in a levain with a substantially different hydration than the dough. The result is bread in which you can taste the wheat, the fermentation, and a subtle chorus of lingering background notes that are all in harmony, without any element of taste outweighing any other.
We use a blend of whole wheat and white flours in the levain at Ken’s Artisan Bakery, and I call for doing the same in this book. This is intended to approximate the excellent stone-ground flours produced by a small number of artisan mills in France. It all started for me with the desire to reproduce a brownish country bread like my baker heroes in Paris were baking, or a bread close to it, anyway, here in the United States.
Bakers often supplement their natural levain culture by adding baker’s yeast to the final dough (not the levain culture). Many of the levain bread recipes in this book call for adding store-bought yeast. This may seem contrary to the purist spirit of levain baking. At first, I felt the same way. When I started my bakery, I set out to create an idealized levain bread made only from a natural culture, without commercial yeast and using sel de mer from the coast of Brittany.
The bread was good. I wish I could taste one of those loaves from the early years right now. But with time I found I wanted loaves with a slightly lighter crumb, a bit more volume, and a more delicate harmony of flavors. And adding commercial yeast was the way to achieve that. It results in greater gas production (and thus more volume), and mellows the dough’s acidity. An alternative way of adding yeast is to mix a poolish at the same time you feed the levain in the morning, and then combine both types of leavening when mixing the final dough. In the summer of 2003, I started doing this at the bakery—mixing a poolish five hours before mixing the levain doughs (Country Brown and Country Blonde), and adding the poolish to the final dough to help it rise. This worked, but the truth is, it’s hard to tell the difference between breads produced using that method and those that have a small amount of baker’s yeast added, and the latter is a practice that has been common in France for over one hundred years. The recipes in chapter 9, Hybrid Leavening Doughs, are leavened with levain supplemented with a bit of commercial yeast, whereas those in chapter 10, Pure Levain Doughs, are leavened solely with levain.
At Ken’s Artisan Bakery, we feed the levain three times a day. There are two reasons why I didn’t go that route in this book. First, my bakery is a lot warmer than the typical home kitchen, so the levain matures much more quickly and needs more feedings to keep it from getting sour. Second, I have bakers present most of the hours of the day. I want to offer you ways of making great levain breads without making you a slave to a schedule that would deter most from repeating the effort. This is a book intended to be used over and over.
Therefore, the schedule for feeding levain in this book requires just a single feeding in the morning, about six to nine hours before mixing the final dough. You can maintain the levain with a single feeding each morning, or you can use it to make dough and then store a chunk of the unused levain in the refrigerator, to be refreshed the next time you want to bake with it. All of those details are discussed in depth in chapter 8.