Learn the science behind:
How to Store Sourdough Starter for Months (And How to Revive It)
Started a sourdough starter for your bread, managed to maintain it for a couple of months, but simply don’t have the time to maintain it the upcoming weeks or months? Maybe you’re going on a trip, or you’re simply in a time of life where your time is scarce. Whatever the reason, it would be great if that hard work of the last few months wouldn’t go to waste. That there’s a way to store your sourdough starter for a while and put it to pause.
Luckily, there is!
What’s in a sourdough starter?
A sourdough starter is alive, as a matter of fact it’s full of micro organisms. The yeasts in your starter will make your bread rise and puff up while proofing. Apart from these micro organisms there’s moisture and food for the micro organisms.
In order for the micro organisms to stay alive and thus for the starter to do its job, it needs both this moisture and food. This is why you have to maintain a starter by regularly feeding it new flour. This flour contains starches and thus sugars for the micro organisms to live from. Together with the flour you will also add water to a starter (generally in a ratio of 1:1). This is to keep the starter moist and liquid. The micro organisms need this liquid to continue to grow and move around. It is a lot harder from them to feed from dry flour.
As long as the starter is alive and moist the micro organisms will keep on growing. As a result, they’ll need new food regularly, allowing them to continue to grow. When you want to store a starter it is therefore a matter of stopping or pausing the growth of the micro organisms.
Drying a sourdough starter
One way to store a starter for a long period of time is to dry the starter. By taking away the moisture, the micro organisms will not be able to grow any more. However, unlike humans, a lot of micro organisms can actually survive a long period without water. They will go in some sort of hibernation mode. Growth of the micro organisms will be stopped, the water activity has become too low to do so. In this dried state a starter can easily be stored for half a year, in some cases even years.
Freezing a sourdough starter
Even though drying is super easy to do, there is an even easier method, but it will require freezer space. Starters can be frozen for at least a couple of months. By freezing the starter you again stop the growth of the micro organisms. Just like a lot of micro organisms can survive in a very dry environment, so is the case for very low temperatures. The growth will be incredibly slow in the freezer.
Our preferred method is drying the starter and we haven’t tried freezing it (yet). But experiences of others seem to allow freezing for at least 6 months.
How to dry a sourdough starter
Drying a starter doesn’t require any fancy equipment. Instead, take an oven rack and place a piece of parchment paper or some plastic foil on top. Now spread the alive starter on the sheet. Try to make the layer as thin and even as you can. Thinner layers dry a lot faster giving you yeasts less chance to do in the meantime.
Place the oven rack in a well ventilated area in your house. Do not place it directly in the sun, but a warm spot is fine. After as little as a few hours only you should be able to see dry spots occuring. Depending on the thickness of your starter and the temperature in your house it should be dry within 2-5 days. It’s better to leave it a little too long than too short though.
Once it’s dried it will be very easy to break the dried starter into smaller piece. Pack it in an air-tight container so it cannot absorb new moisture again. If you seen condensation forming on the inside of the container, the starter hasn’t yet dried enough. Take off the lid and leave to dry for at least another day.
Reviving a dried sourdough starter
Reviving the starter is very easy, certainly easier than making a new starter. Take the dried starter, about 10 grams will be more than enough. Place it in a closer container with approx. 100ml of water and 80-90g of regular flour. Wait a few days until you see bubbles forming. If you see bubbles, continue the same way as you would when making a new starter. Pour off half of the starter and add equal amounts of water and flour. Leave for another day, from now on, treat it just like you would any other starter.
If you’d like to gift someone some starter giving them some dried starter is a great idea. It won’t force them to start immediately, they can start at any moment that’s convenient to them. Also, it ships very easily, especially since you need only very little.
I had no idea one could do this! Is it best stored as sheet-like pieces as pictured or can it be crushed up for more compact storage and precise measurement?
You can definitely crush it up more, that shouldn’t harm it. Generally speaking, you don’t need to be as precise with measurements when reactivating this since most of the mass will come from the added flour and water. It really gives your starter a quickstart by adding the right mix of microorganisms.
Glad to hear you found it helpful! It can take you off the sourdough hamsterwheel of feeding if for whatever reason you need/want to.