What is Potato Flake Sourdough Discard?

If you’ve been maintaining a potato flake sourdough starter, you’ve likely come across the term “discard.” But what exactly is it, and how does it differ from an active starter or a traditional flour and water sourdough starter? When you have your own starter, many questions may arise, let’s answer them below.

Understanding Potato Flake Sourdough Discard

The term “discard” refers to the excess starter that you remove when feeding your potato flake sourdough starter. When you feed your starter with sugar, instant potato flakes, and water to keep it alive and active, you’ll often have to remove a portion of it to prevent it from growing too large. The removed unfed portion is what we call the discard.

You only need to keep about one cup of the starter in your jar to feed. Keeping more than that will cause you to need to feed it more 

Unlike an active starter, which is bubbly, foamy, and thriving with yeast activity, discard has not been recently fed and is not as active. Think of it as a starter in a resting state—it still contains natural yeasts and good bacteria but lacks the strength needed to make bread rise on its own, or it would take a very long time for it to do so.

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​Helpful tools to maintain a starter:

Glass Jar: I love using a large glass jar, it’s also helpful to get one with measurements on the side to make it easier to see how much starter you have

Wooden Spurtle: This is my favorite tool for stirring my existing starter before using in a recipe, of when feeding my remaining starter. 

Cloth Bonet: This is the most ideal way to cover your starter and prevent bugs and dust from getting inside. 

This kit has the jar and cloth bonnet, it does come with a silicone spurtle, which is a great deal if you are wanting to get them all. 

When Will I Have Potato Flake Starter Discard?

Every time you feed your potato flake sourdough starter, you will likely generate discard. Here’s why:

• You typically maintain 1 cup of starter before feeding.
• During feeding, you add 1 cup of water, ¾ cup of sugar, and 3 tablespoons of potato flakes to your starter.
• After feeding, your starter will grow to nearly 3 cups in volume.
• When baking, you’ll usually remove ½ to 1 cup of starter for recipes. If you don’t use more of the active starter in another recipe, you will have extra.
• Before the next feeding, you must remove the excess starter (enough to leave 1 cup in your jar) to maintain a manageable size, otherwise you will need to feed it a larger amount.
• The extra unfed portion removed is the “discard.”

Potato Flake Sourdough Discard vs. Flour & Water Sourdough Discard

There is a key difference between discard from a potato flake sourdough starter and a flour and water sourdough starter:

• Flour and Water Starter Discard: Since this type of starter already contains flour, some discard recipes allow you to bake immediately without adding additional flour. The flour in the starter has already gone through fermentation, giving the baked goods a tangy sourdough flavor.
• Potato Flake Sourdough Discard: Since this starter does not contain flour, any recipe using it must include flour separately. For full fermentation benefits, you should let the dough ferment before baking.

Questions About Potato Flake Sourdough Discard:

Can Discard be left at room temperature?

No, unlike an active starter that is regularly fed, discard should be stored in the refrigerator if not being used within a day or two. It will die quickly if left at room temperature for too long.

How long is discard starter good for in the refrigerator?

I can say for certain that Potato flake sourdough discard can last up to 2-4 weeks in the refrigerator. However, the longer it sits, the less active it will become. Eventually losing the ability to ferment any recipe. Discard can last several weeks in the fridge without ever being touched. It can last even longer if you are continually adding new discard starter to the same jar. This is because the new starter you will be adding will have some amounts of “food” left that will keep the wild yeast from dying. 

Do I have to bring it to room temperature before using?

Not always. It depends on the recipe. If you’re using discard in baked goods like pancakes, waffles, or muffins, you can use it straight from the fridge. However, if you’re incorporating it into a dough that requires commercial yeast, bringing it to room temperature can help with better fermentation.

It’s also a good idea to use discard that is room temperature when adding coconut oil because if you don’t the cold discard will harden the coconut oil making it harder to incorporate into the recipe. Some discard recipes call specifically for cold starter, so it’s important to read over your recipe to decide if cold or room temperature starter is the best option. 

Can I use discard as a replacement for liquid in any recipe?

It depends. Potato flake sourdough discard contains both liquid and some solids from the potato flakes, so it can be used to replace a portion of the liquid in recipes like pancakes, muffins, and quick breads. However, because of its consistency, it may slightly alter the final texture. You might need to make slight adjustments to the recipe for the best results. 

Does discard starter cause a different taste and texture compared to active starter?

Yes. Discard starter can have a stronger flavor and doesn’t contribute as much rise as a fed starter. Using an active starter or discard will not change the flavor or the texture drastically in a “discard” recipe, especially if you ferment prior to baking. 

Do you remove the discard before or after feeding your starter?

You remove the discard before feeding your starter. This prevents overgrowth and keeps the starter balanced by removing excess before adding fresh food (3 tablespoons potato flakes, 3/4 cup sugar, and 1 cup water).

How does using discard affect the gluten in a recipe?

Discard can still ferment the flour that it is added to, it just may take longer for it to ferment. Either way, the fermentation process decreases the amount of gluten in the final product, but with discard it will need to ferment longer if you are wanting the least amount of gluten possible. 

Can you freeze discard potato starter?

Yes! You can freeze potato flake sourdough discard in an airtight container or a freezer bag for up to 2 months. Thaw it in the refrigerator before using, and stir well before incorporating it into recipes. Revive it by feeding it a few times prior to baking a loaf of bread, or thaw it and use immediately in a discard recipe. 

Can you use potato flake sourdough discard in recipes that call for flour and water sourdough discard?

In most cases, yes! It will need some adjustments though. Potato flake starter contains more liquid and will alter the recipe if adjustments aren’t made to the liquid/flour ratio. While potato flake sourdough discard has a slightly different composition and more sweetness due to the sugar content, it can often be substituted in non-yeasted recipes like pancakes, muffins, crackers, and cakes.

Traditional flour and water sourdough discard contains fermented flour, meaning it has already undergone some gluten breakdown. Potato flake sourdough discard, however, does not contain flour and must have flour added separately, and then allow for fermenting time, of you want it to have the fermentation benefits.

Do you need to feed discard before using it?

No, discard is inactive, meaning it doesn’t need to be fed before use. It’s ready to go as-is in recipes. If you feed the discard, it won’t be discard any more, it will become active starter. 

Discard, is it the same thing as waste?

No! Potato flake sourdough discard is an inevitable byproduct of maintaining your starter, but it doesn’t have to go to waste! While it’s not as strong as an active starter, it can still be put to good use in a variety of recipes.

Discard is simply the portion of the starter that is removed before feeding to maintain balance. It’s still full of flavor and nutrients and can be used in all sorts of recipes, making it far from wasteful.

In fact, finding creative ways to use discard is one of the best parts of maintaining a potato flake sourdough starter! Whether you choose to let your dough ferment for added benefits or bake immediately, understanding the role of discard helps you make the most of your potato flake sourdough starter.

Can Discard Can Be Used Like an Active Starter?

In some cases a starter that hasn’t been fed in a few days will still work the same as an active starter. This is not always the case.  Some believe that discard can replace an active starter in recipes that require rising, but discard lacks the necessary yeast activity, causing a very long rise time. If a recipe calls for an active starter, using discard alone may result in a dense or flat bread. While you might get lucky and have discard rise a loaf or two, it’s not a reliable way to use a potato flake sourdough starter.

Do you have to “bulk ferment” when using discard?

Not necessarily. Although, fermenting isn’t necessary when you are adding additional leavening agents, fermenting with discard can enhance its nutritional benefits. I almost always include the fermenting directions on all of my potato flake sourdough recipes, because of the benefits. 

It’s not necessary for every recipe, and there are occasions when you don’t have the time to allow it to ferment. Many quick recipes, like pancakes or cookies, can be made immediately with discard without the need for fermentation.

Fermenting your dough helps to break down gluten and phytic acid, an antinutrient found in grains that inhibits mineral absorption. The longer the fermentation process, the more it improves digestibility and nutrient availability (of course, you don’t want to over proof). If you choose not to ferment, keep in mind that it may slightly alter the flavor and texture of your final product.

Best Potato Flake Sourdough Discard Recipes:

Potato flake sourdough discard is perfect for recipes that include additional leavening agents. A good way to use up discard is by using one of these recipes:

• Pancakes
• Crepes
• Muffins
• Crumpets
• Quick breads (like banana bread, pumpkin bread, and zucchini bread)
• Crackers
• Cookies

Since these recipes typically do not rely on the starter for leavening, they allow you to use up discard without worrying about fermentation or proofing times.

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