Once a sourdough starter has been rehydrated and made vigorous, maintaining the sourdough starter often begins with discarding a portion of that starter. This practice seems confusing and can cause frustration.
The confusion rightly stems from a question of why. Why should one toss a perfectly good portion of sourdough starter? The reason is that unless some starter is discarded, it quickly builds up and requires so much flour for feedings that it becomes unmanageable. For a more lengthy discussion of this question, consult this blog post on discarding sourdough starter.
The frustration comes in when trying to determine what to do with the discarded portion of starter. It can be thrown in the trash, put in a compost heap or shared with a friend. Or, discarded starter can be used in a variety of baked goods.
Not all recipes work well using discarded sourdough starter. A fluffy loaf of sourdough bread is best baked with a well-fed, active starter that will impart flavor, fermentation, and leavening to the process. There are other recipes, however, that do well with discarded starter.
WHEN To Use DISCARDED SOURDOUGH STARTER?
A recipe generally works well using discarded sourdough when it meets some or all of the following criteria:
- The hydration called for in a recipe matches that of the starter.
- Sourdough starter is included for flavor or sourness and not for fermenting the grains.
- Sourdough starter is included for flavor or sourness and not the leavening ability of the sourdough starter.
- No leavening agent is required.
FERMENTED VS. UNFERMENTED DISCARDED STARTER Recipes
The recipes that meet the above criteria can be broken down into three categories:
- Sourdough Flavor, Unfermented Flour. Recipes that call for added flour, no fermentation or soaking time, and are baked immediately. The sourdough starter adds flavor but the flour or grain in the final product is unfermented.
- Sourdough Flavor, Fermented Flour. Recipes that include additional flour which is fermented (or soaked) for some time before baking. The sourdough starter not only adds flavor in this case, but the flour or grains in the final product are fermented.
- Sourdough Flavor, No Flour Added. Recipes that call only for discarded starter and no additional flour, and therefore have no need for further fermentation.
#1 Sourdough Flavor, Unfermented Flour
These are the recipes that utilize the discarded starter for flavor and as a means of using up that discarded starter. They generally combine sourdough starter with additional flour, liquid ingredients, and leavening. The bread is baked right after mixing, like quick breads are, and so a portion of the grain is left unfermented.
#2 Sourdough Flavor, Fermented Flour
For pre-digestion of the grains through fermentation, discarded sourdough can be used as well as fresh starter. The discarded starter is added to additional flour and liquid and fermented for 12-24 hours. In this case, a leavening agent such as baking soda is added to react with the acidity of the starter and create gases that are trapped within the structure of the flour-water mixture to create leavening.
#3 Sourdough Flavor, No Flour Added
Similar to case #2, above, discarded sourdough is used in recipes with no additional flour called for, so it can be baked immediately. The discarded starter’s flour is already fermented and it adds sourdough flavor to the recipe. An additional leavening agent is added to this type of sourdough as well.