How to Dehydrate and Rehydrate Your Sourdough Starter

I love my sourdough starter, but maintaining it can be a labor of love. If you want to take an extended break from baking or simply keep a reliable backup, learning how to dehydrate and rehydrate your starter is a useful skill to have.

Dehydrating your sourdough starter is an easy way to preserve it for long-term storage, create a backup or share it with another baker. All you need is an active starter, parchment paper and a little patience.

In this guide, I'll show you how to dehydrate sourdough starter without a dehydrator, store it safely and rehydrate it when you're ready to bake again.

A dehydrated starter protects your starter from mold, neglect, and accidents. No matter what happens, you will always have a sourdough backup.

Why I Keep a Dehydrated Backup

I first started thinking about preserving my starter after I accidentally baked mine. I had placed it in the oven with the light on to encourage it to grow more quickly on a cold winter day. I forgot it was in the oven and started preheating the oven to fix some chicken nuggets for my son.

Luckily, I had some recently discarded starter in the refrigerator that I was able to revive, but I knew I needed a more reliable backup.

Once dehydrated, all the good bacteria and yeast that give your sourdough lift and flavor are still there, waiting for reactivation.

If you need help creating your own sourdough starter check out this post: How to Create and Maintain a Small Sourdough Starter

You can also use the Scrapings Method for Maintaining a Sourdough Starter to minimize your sourdough discard, Store Your Sourdough Starter in the Refrigerator, or Keep Your Starter at Room Temperature.

When Should You Dehydrate Your Sourdough Starter?

Consider dehydrating your starter if you're taking an extended break from sourdough, traveling for a long period, want to share your starter with someone or simply want a backup in case something happens to your active starter.

You don't have to choose between maintaining an active starter and keeping a dehydrated one. I keep dried starter as insurance even when I'm actively baking.

How to Dry Sourdough Starter for Storage

For the best results, start with an active and healthy sourdough starter that was recently fed and is bubbly. I also suggest waiting until your starter is mature, meaning it is at least a few months old.

Tip: A sluggish or unfed starter may not revive as well after dehydration. If needed, feed it a day before dehydrating and allow it to reach peak activity.

Step 1: Line a baking sheet with parchment paper or a silicone baking mat. Pour a thin layer of active starter onto the parchment paper and spread it evenly using an offset spatula. The thinner the layer, the faster it will dry.

Step 2: Let the starter dry completely at room temperature in a dry, well-ventilated area. This can take anywhere from 12 to 24 hours depending on the humidity.

Tip: I leave my starter on the counter with my kitchen's ceiling fan on to provide some air flow.

Tip: Don't be tempted to place your starter in a low oven. The lowest setting on my oven is 170°F (76°C). That is too warm and will kill the yeast in your starter.

Step 3: Once the starter is completely dry, brittle, and easy to break into flakes, break the dried starter into small pieces or grind it into a fine powder using a food processor or blender.

Step 4: Store it in an airtight container, glass jar, or vacuum-sealed bag in a cool, dark place. Label it with the date and contents.

Tip: If any areas are still sticky or soft, allow it to dry longer. Once dry, your starter should weigh half as much as it did when it was still wet.

How to Speed Up the Drying Process Without a Dehydrator

The fastest way to dehydrate a sourdough starter is to use a dehydrator.

1. Line the tray for your dehydrator with parchment paper. Pour a thin layer of active starter onto the parchment paper and spread it evenly using an offset spatula. The thinner the layer, the faster it will dry.
2. Set your dehydrator to 95-100°F (35-38°C).
3. Dehydrate for 4-6 hours until the starter is completely dry.

If you want to dry your starter out faster, but don't own a dehydrator, I have two suggestions.

• Heat your oven to its lowest temperature and then turn it off. Place an oven thermometer inside of the oven and only add your starter after the temperature has dropped below 98°F (37°C).
• Or place the starter that has been thinly spread across a piece of parchment paper in the oven, close the door, and turn on the oven light. The gentle heat from the light bulb will speed the drying process up. Similar to using a 100-watt lightbulb in an Easy Bake Oven.

Tip: If you do decide to use your oven, I suggest placing a post-it note or towel over the oven's on button to prevent someone from accidentally baking your starter.

Troubleshooting Dehydrating Sourdough Starter

• Starter is not drying properly: Ensure the layer is thin and placed in a dry, ventilated area. If using an oven, keep the temperature below 100°F to avoid killing the yeast.
• Starter develops an off smell while drying: This could be due to contamination. Always use a clean surface and dry it in a low-humidity environment.
• Dried starter is too sticky: If it remains tacky, it has not fully dried. Allow it to air dry longer or use a dehydrator at a low temperature.

How to Store Dehydrated Sourdough Starter

Once your starter is completely dry, break it into flakes or grind it into a powder. Transfer it to an airtight container, vacuum-sealed bag or zip-top bag and store it in a cool, dark, dry place.

Before sealing the container, make sure the starter is completely dry. Any remaining moisture can encourage mold. Label the container with the date so you know when the starter was dehydrated.

It is not necessary to refrigerate or freeze your dehydrated starter for long term storage. I currently have a jar of dehydrated starter sitting in my pantry that is two years old.

How to Rehydrate Dried Sourdough Starter

Reviving your starter is easy.

Step 1: Stir together 15 grams of dried starter and 30 grams of water. The sourdough flakes should be completely submerged. Allow the mixture to sit for 1 hour stirring occasionally until the sourdough flakes have completely dissolved.

Step 2: Add 15 grams of flour and 15 grams of water. Stir to combine.

Wait until the mixture is nice and bubbly and has doubled in size. The length of time this will take will depend on the temperature of your home.

Tip: If you have ground your dried sourdough into a fine powder you can probably skip the soaking portion of step 1. Go ahead and add 15 grams of dried sourdough, 15 grams of flour, and 45 grams of water to your jar and stir to combine. Wait until the mixture is bubbly and doubled in size and proceed to step 3.

Step 3: Discard all but 20 grams of the starter. Add 20 grams of flour and 20 grams of water. Stir well and let sit at room temperature for twelve hours. It should double in size.

Step 4: To strengthen your starter, feed it twice daily, discarding all but 20 grams and feeding it equal amounts of flour and water each time, until it becomes bubbly and active. This usually takes 3-5 days.

Once your starter is consistently rising and doubling in volume, it's ready for use.

You can then return to your regular storage method and feeding schedule. Not sure which storage method to return to? Take my Sourdough Starter Storage Quiz to find the method that best fits your baking routine.

Troubleshooting Rehydrating Dried Sourdough Starter

• Starter does not dissolve in water: Try breaking it into smaller flakes or letting it soak longer before adding flour.
• Starter is not bubbling after several feedings: Ensure you are feeding with equal parts flour and water by weight. It may take longer if the original starter was weak before dehydration.
• Starter has a strange smell after rehydration: A slightly sour smell is normal, but if it smells rotten or moldy, discard and start over.
• Starter is not doubling in size: Continue feeding twice a day and keep it in a warm environment (70-75°F) to encourage yeast activity.

Tip: A cold kitchen could slow down the reactivation process. To speed this process up, place the rehydrated starter in your oven with the oven light on. The inside of your oven should heat up to about 85°F (30°C).

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