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Small mason jar filled with flakes of dehydrated sourdough starter, with a small wooden spoon full of starter flakes in the foreground, and a large mason jar full of active sourdough starter in the background.

Dehydrated Sourdough Starter

If you bake sourdough, you need to make a backup of your starter in case anything goes wrong. It's quick and easy, and can be stored indefinitely!
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Prep Time 5 minutes
Cook Time 1 day
Total Time 1 day 5 minutes
Servings: 1 portion
Ingredients Equipment Method Notes

Ingredients
  

  • active sourdough starter exact amount doesn't matter

Equipment

  • 1 baking sheet
  • 1 rubber spatula or offset spatula (like for spreading frosting)
  • 1 silicone baking mat or sheet of parchment paper

Method
 

  1. Line a baking sheet with a silicone baking mat or sheet of parchment paper. Take some active sourdough starter and spread it out very thinly. The thinner you spread it out, the faster the starter will dry.
  2. If you have low humidity in your home (less than 45% RH or so), you can leave it out on the counter uncovered. If your home is more humid than that, put it in the oven with the door closed and the light turned on. Make sure to put a sign on the oven door to prevent anyone from accidentally preheating the oven and cooking the starter.
  3. It could take anywhere from 2–24 hours for the starter to dry. Once even the thickest parts of the sheet of starter are dry, break it up into small enough parts to fit in an airtight ziploc bag or mason jar. Or you can put pieces of the dry starter into a blender or food processor and grind it into small pieces or even a powder, and then store that in an airtight container.

Notes

If you have a food dehydrator, use that instead! In that case, ignore the instructions to use a baking sheet. Instead, spread the starter out thinly on a piece of parchment paper that will fit on one of your dehydrator pans, and dehydrate according to your machine's instructions. Set the dehydrator to 88˚F (31˚C) and dehydrate for 4-6 hours
The dehydrated starter backup will keep indefinitely if stored in an airtight container in dry conditions.