Fermenting Sourdough Starter.
Jessica Hardiman © 2025 HGIC, Clemson Extension
What Is a Sourdough Starter and How Does It Work?
A sourdough starter is an active culture of water and fermented flour, thriving with beneficial bacteria and wild yeast.
These microorganisms ferment the flour, producing the bubbles and rise needed for bread-making.
What Is Sourdough Discard?
Sourdough discard is the portion of the starter that is removed before feeding.
Lots of bakers throw it away, but it can still be used in many recipes.
Why Feeding Your Sourdough Starter Is Important
Feeding is crucial because it helps keep the microorganisms in your starter healthy and strong.
You should notice that each time you feed your starter, it bubbles and increases in volume.
This means it is happy, healthy, and well-fed.
If it doesn’t have many bubbles or doesn’t rise very quickly, try feeding it more often.
Why You Must Discard Sourdough Starter Before Feeding
Unless you are baking with your starter every day, if you do not discard some of it before feeding, you will end up having to feed it exponentially each time.
For example:
- 30 grams of starter will be fed 30 grams of flour and 30 grams of water
- The next time you feed it, if you don’t discard any starter, you will start with 90 grams of starter and feed it 90 grams of flour and water.
See how that could get out of hand quickly?
How to Use Sourdough Discard Instead of Throwing It Away
Many people throw away the starter’s discarded portion when they feed it.
Instead of wasting it, there are plenty of delicious recipes you could use it in.
Using discard adds a unique fermented flavor to baked goods.
Sourdough Discard Recipes to Try at Home
See various recipes from King Arthur Baking below:
