Bread & Sourdough

How Long Can I Keep Sourdough Discard in the Fridge? 

It’s a common question among sourdough bakers. How long can sourdough discard stay in the fridge? You don’t want to throw the discard away, it’s a great ingredient to use in several baked recipes.

Sourdough discard has an infinite lifespan in the refrigerator. As long as your fridge keeps the discard cold, the liquid will last forever. However, it doesn’t mean you want to use discard from several months ago. It does degrade over time.

So, how long can you keep sourdough discard in the fridge? You can store the liquid for about one week in a refrigerator before developing a strong, acidic taste.

What Is Sourdough Discard? 

Your sourdough needs a starter, but there’s a portion you remove. Sourdough discard is the liquid you take out of the starter, before feeding.

The unfed starter is the discard, and it’s good for more than composting. It has the same tangy taste as sourdough, giving your baked recipes additional flavor. Some recipe ideas include dark chocolate cake and breakfast crullers.

Don’t forget to mix the discard during the first week of storage. You want to start the fermentation process to remove any bad bacteria. When the liquid starts bubbling and rising, it is ready for use.

How Should You Store Sourdough Discard? 

After removing the discard from the sourdough starter, the best place to store the liquid is in a container with a loose lid. Oxygen helps with the fermentation process and the lid keeps impurities out of the sourdough discard.

You can leave the lid unscrewed and the jar on the counter if you are planning on using the discard in a few hours. Otherwise, store the sealed discard jar in your refrigerator. Your discard will still start fermenting, only at a slow rate keeping the liquid useable longer.

How Long Does Sourdough Discard Last in the Fridge? 

Sourdough discard is usually at its best for one week. Even though the constant cool temperature slows fermentation to a crawl, the discard still breaks down. After seven days or so, sourdough discard often develops a sour taste. Acidity levels also increase, which can affect how it reacts with other recipe ingredients.

The age of your sourdough discard also affects its lifespan. Discard older than six months has an indefinite lifespan in the fridge. You can revive the liquid as needed.

Discard younger than six months have a shorter lifespan in the refrigerator. The bacteria and yeast colonies are still developing, but there is a way you can extend their life.

How to Extend the Life of Your Sourdough Discard 

You can extend the life of sourdough discard in the fridge, by adding new liquid to the jar. The addition of fresh bacteria and yeast works to prevent the discard from breaking down.

It can prevent high acidity levels and keep the taste from becoming overwhelmingly sour. You still want to use the discard within a couple of weeks if you aren’t adding more liquid.

Is Your Sourdough Discard Going Bad? 

It’s not always easy to know if your sourdough discard is going bad. The liquid has a strong acidic smell, even after a couple of days. It’s not an unpleasant scent, but it can mask other odors released from bad yeast or bacteria.

Sourdough discard rarely goes bad in the fridge when the temperature stays around 37°F. It’s the standard factory setting for most models, so you don’t need to adjust the internal temperature.

If the refrigerated discard is starting to show signs of mold, it’s time to toss the liquid. The mold usually appears as a pink or orange hue in the discard.

What Can I Do With Old Sourdough Discard? 

You can find plenty of recipes calling for old sourdough discard in the ingredients. Don’t forget to pay attention to the liquid’s age.

Fresh discard works best in sweeter recipes, while savory dishes explode with flavor when you add older liquid. Newer discard is less acidic and has a lighter flavor that blends better with sweet dishes.

Sometimes you end up with some leftover sourdough starter. The active liquid does not easily store, but it still has a use. You can add the extra starter to any of your sourdough discourse recipes that include crackers and apple fritters.

Do You Have to Discard Sourdough Starter? 

Not everyone wants to use sourdough discard in recipes. They prefer to forego straining and save the unfed liquid.

You do not have to save the liquid. It’s safe to go down the garbage disposal. You can also add sourdough discard to a compost pile. It counts as a layer of liquid that also adds beneficial bacteria that helps in decomposition.

It doesn’t matter what you do with the removed liquid, as long as you have enough room in the jar to feed the sourdough starter.

Can You Make New Sourdough Starter From Discard? 

You can use old, refrigerated discard to make a new sourdough starter. It only takes two common kitchen ingredients, flour, and water.

Remove around 50g of discard from the jar. Add the same amount of water and flour to the liquid. Keep adding the ingredients to the discard until it starts bubbling and rising. You now have an active sourdough starter to use in your recipes.

Creating a new starter from old discard is also a great way to reduce waste. Instead of removing liquid from the jar, you are adding flour and water.

How to Keep Sourdough Discard Ready for Use 

Frequent bakers may want to consider keeping their jar of discard ready for use. It saves some prep time and reduces waste.

You don’t need to be a daily baker to keep your discard ready to turn into a sourdough starter. The process is known as micro-feedings, and it only takes a few minutes of your time on non-baking days.

Micro-feeding starts with around 5g of sourdough starter. Go ahead and mix the starter with 15g of water and 15g of flour. It’s enough to keep the cultures active without speeding up fermentation. You are only creating a base for the next time you bake.

With micro-feedings, you are eliminating waste, but you are also limiting the amount of sourdough starter you have on hand. You may not have enough for every sourdough recipe.

Creative Ways to Use Excess Sourdough Discard 

Frequent bakers can quickly become overrun with sourdough discard. You don’t want to overpack your refrigerator with the liquid. It also only lasts for a week or two, and very few homes do that much baking.

It is okay to throw sourdough discard away. You are not harming the environment or your garbage disposal. Adding discard to a compost pile is an eco-friendly disposal method your plants will appreciate. You can also gift your excess sourdough discard to friends and family new to baking.


You can keep sourdough discard in a fridge for a week or two before it starts breaking down. Along with using the liquid in sourdough discard recipes, you can also use it to make a new starter.

Sourdough discard does have an indefinite shelf life in the refrigerator, but it also doesn’t mean you want to use the liquid after a few months. Older discard has a high acidity level that affects how your recipes turn out.