Sourdough starter and levain (leaven) are both integral parts of the sourdough bread-making process. Read on for a more detailed explanation.

Sourdough Starter ≈ Levain

At their core: they are the same. They go through the same fermentation cycle. Both are fed flour and water. Their PURPOSE is different.

Sourdough Starter

Sourdough starter is a culture of yeast and bacteria. It is continually maintained in the same way at regular intervals (daily, weekly etc.). A small bit of sourdough starter is fed, ripens (rises/bubbles) and needs to be refreshed in a continual cycle. The fermented starter that doesn’t get refreshed becomes the discard. Some important points to remember:

• Sourdough starter should never be used up entirely in a single bake.
• Sourdough starter can be used indefinitely if maintained properly.
• Sourdough starter is usually refreshed with the same type of flour.
• Sourdough starter is sometimes referred to as the “mother” starter. It is continually refreshed and a small part of it is used to make every levain. This results in the “mother” starter actually being in every loaf of bread you bake.

Levain

Levain (or leaven) is an offshoot of your sourdough starter. It is a mixture of starter, flour and water that has unique characteristics. A levain is created for a specific recipe and will be used entirely in the day’s bake.

• Levain can be used to alter the flavor and texture of your final dough with any flour combination. For example: When making rye bread, you may use a combination of rye and bread flour. In baking my favorite sourdough white sandwich bread, I use a levain that has added sugar and sometimes even double the flour–for a stiff levain.
• Levain is used up entirely in a single bake.

How do I use Levain in a recipe?

Based on the recipe’s instructions, take a small amount of your sourdough starter and put it in a small bowl or liquid measuring cup. I like using liquid measuring cups that are clear and well-marked, making it easy to watch the levain rise. Add flour and water to the sourdough starter in a separate bowl. Some recipes will also call for sugar or various quantities/types of flour added into the levain, something you would not add to your sourdough starter. The required amounts will depend on the recipe. Often you will mix your levain the night before you mix your bread. Sometimes you can mix your levain the day of (it depends on the recipe). The levain is kept separate from your starter, even though the process of creating levain is almost identical to feeding a starter.

When is a Levain ready to be used?

Levain follows the same fermentation cycle that sourdough starter does.

1. Just Mixed Levain– fresh smell, no sourness, little to no rise, no bubbles
2. Young Levain–sweet with just a touch of sour notes, beginning to rise, scattered bubbles
3. Ripe Levain–sour undertones, doubled in size, many bubbles, just reached its highest point and is starting to go back down MAKE YOUR BREAD when the levain reaches ripeness
4. Overripe levain–bubbly/frothy/liquidy, collapsing in the jar sour smelling/vinegary  MAKE YOUR BREAD NOW
5. Very overripe starter– layer of “hooch” on top, very liquidy, vinegar/harsh nail-polish type smell–Start over, your levain has fermented too long and won’t have enough active yeast to leaven your bake

As soon as the levain is ripe (doubled or tripled in size, bubbly, rounded at the top and just starting to come back down), it is time to bake with it. At this ripe stage, levain has the most yeast and best flavor profile for your bake. If you forget about the levain and it becomes over-ripe, you can still bake with it. The bake may be a little more sour than desired but should work fine. If your levain is very overripe with a layer of hooch on top, very liquidy and smells harsh–start again.

What If I forget to make a Levain? Can I use Sourdough Starter Instead?

Yes! In a pinch, you can use ripe sourdough starter. Just make sure you have some leftover to feed so you replenish your starter and don’t use it all up. You could also build a “fast” levain using a 1:1:1 ratio (100% ripe starter, 100% flour, 100% water) which should be ready in about 3-4 hours if kept at 78 degrees.

A recipe calls for Bubbly Sourdough Starter, not a Levain. Help!

Sourdough has been around for thousands of years. It is the traditional method of leavening and baking bread. Making a levain for your bread is what I consider a “best practice” in sourdough, not necessarily that you can’t make good bread without one. Many recipes will call for “1 cup bubbly sourdough.” I interpret that as 1 cup of ripe levain (or sourdough starter if your starter produces enough). These recipes can also be difficult to understand especially if using volume measurements like cups: How much is exactly one cup of bubbly sourdough? Do I stir it down? Measure it based on height? I much prefer recipes that use metric measurements.