What is levain?
Levain, also known as leaven, is the fed starter to be used for the purpose of sourdough bread making.
It is different than sourdough starter in that when building levain, it is common to feed the starter more than its typical feeding ratio (typically 1:1:1 starter-water-flour) to ensure peak activity when proofing the dough. It is also common to add additional ingredients, like sugar, to build a special type of levain, like sweet levain, for specialized bakes. Because of this, levain builds can be use to alter the flavor and texture of a sourdough bake.
Comparison chart
| Sourdough Starter | Levain |
| Ongoing culture, fed & discarded regularly | Built once for a single bake |
| Typically is made up of water, flour, and starter | Can be made up of many different ingredients |
| Typically fed at 1:1:1 ratio of starter-flour-water | Usually fed at a higher four and water ratio |
