Levain is a leavening agent or bread starter, also known as a chef, which is frequently used in place of yeast to rise dough. It’s French in origin, and food historians estimate it has been in use since the 1600s. It may also be called sourdough, leavening, or wild yeast. The date on this “chef” is somewhat misleading, since it’s estimated that creating leavening agents like levain was the work of the agent Egyptians, at least 6000 years ago.

People often prefer the predictability of baker’s yeast to levain, since yeasts can rise bread within a couple of hours. Starters take several days to make, and you may have to wait more than two to three hours for bread to rise satisfactorily. Despite the lengthier time involved in using this leavening agent, many artisan bakers prefer it as more natural than baker’s yeast.

To make levain, water and flour are mixed together and allowed to sit out in the open for several days. This exposes the starter to air and encourages the natural growth of fungus and bacteria. The fungus or yeast that grows tends to inhibit the growth of dangerous bacteria, making levain safe to use as a food.

Once the levain is prepared, a process that under the best of circumstances usually takes at least a day, bread dough is mixed with the starter, and the mixed dough will naturally rise. As with bread risen with baker’s yeast, temperature can make a difference in how quickly bread rises. Dough should be covered and stored in a warm place with no drafts for quickest rising.

Most people who use levain maintain it, rather than simply remaking it each time they make bread. Once the chef is mixed into bread dough, a portion of the bread dough is removed, put back in the starter receptacle and remixed with flour and water to maintain the starter so it is readily available for the next batch of bread. If you’d like to try this starter without going to the trouble of making it, try to find a friend that’s already got a starter going who will loan you a cup. You can then easily maintain your own chef thereafter, by removing a cup of the mixed bread dough, and following the steps above.

Some people maintain starters for years, and others gradually grow tired of them and start over. It’s important to inspect the starter receptacle from time to time. If you note blue or green mold, bad bacteria has clearly taken over and you should start fresh. In most cases, you’ll note that levain has a sour smell, and there may be some condensation. This is natural, since the production of natural fungi produces gases, which may condense into liquid form.