Drying a sourdough starter is a common option to preserve it for a long time. A dried starter can not be used directly. It has to be reactivated first. This is how you do it.

When drying a sourdough starter the once lively microbes begin sporulating. The microbes fall asleep and hope for a better time soon. This is the reason why you can cultivate a starter from flour in the first place: The flour contains thousands of sporulated microbes. After mixing flour with water they become active again.

Fun fact - some scientists have found almost 100 million-year-old yeast spores (Jure Piskur et al. “Molecular Mechanisms in Yeast Carbon Metabolism”). If you read about scientists re-activating sourdough from Egyptian tombs - this is the reason.

Steps

To reactivate a dried starter simply take a tiny bit (a fingertip) and mix with around 50g of water and 50g of flour. You can choose any flour that you have at hand (yes even gluten-free flour). Make sure to thoroughly knead your mixture.

The microbes will become alive again. The flour provides them with the food they need to multiply again. As they become alive they will start to outcompete other microbes from the flour/water mixture and take over.

Let your mixture sit for 24 hours. Depending on the temperature you might be able to see some pockets of air already on the edge of your container. Also, note the smell of the mixture. It should start smelling slightly sour and either vinegary or yogurty.

On the next day take 10g from the previous day and mix again with 50g of flour and water. Discard the rest for now. There might be some unwanted fermentation. Note the smell again and potential air pockets in the starter. Your starter might also have increased in size (depending on the flour you use). It’s always safer to use the nose and check for air pockets, rather than going by size increase.

Once your starter begins to have the vinegary/yogurty smell it is ready to be used to make a dough. It can also happen that your starter needs a few more feedings to be re-activated. Simply repeat the steps listed above and wait until your starter has the correct signs.

Making a dough

Use the ready starter to make your dough as usual. If you are just getting started I recommend making some flatbreads. If you would like to deep dive into wheat sourdough check out this chapter in my book. Maintenance of the starter goes a bit beyond the scope of this article. You can read more about starter maintenance here.

Happy baking!

Random nerd knowledge

Fun fact - this is the reason why supermarket-dried starters always contain additional pure commercial yeast. The wild microbes take a while longer to become alive again. It would take 24-48 hours for the dough to be ready. This long timeframe would be too long for making a wheat-based dough, the flour would break down too much. I wonder if continuously drying, activating and drying could potentially make an instant dry sourdough starter? I will keep trying and report back.

If you are looking to buy my starter “Bread Pit” you can do so via this link. Don’t use all of the dried starter when reactivating. Share some of it with your friends or store it in a dry dark place for later use.