Maintaining a sourdough starter is a fun process that requires much less work than a traditional pet! It is also the key to making delicious homemade sourdough bread. This is a much easier process than many imagine. In fact, as you will see, your sourdough starter, stored properly, can last weeks or even months without any help from you. With semi-regular feedings, your sourdough starter can be with you for as long as you like. In this post, I will answer common questions beginners and provide a few tips.
First, it is important to understand what exactly is a sourdough starter. At its simplest, a sourdough starter has only two ingredients: flour and water. However, an active starter is so much more than this. Inside this mixture live billions of bacterium and yeasts that eat the flour and produce useful byproducts. For the purposes of baking sourdough, two of these byproducts are of primary importance: carbon dioxide and lactic acid. The carbon dioxide causes our bread to rise and the lactic acid gives it the characteristic sour taste.
In order to keep the bacteria alive it is important to feed them. In this section I address the basic process of feeding a starter.
While there are many approaches to feeding, I prefer a simple approach. As a basic rule, always feed your starter equal proportions, by weight, water and flour. However, this simple rule does not say how much water and flour to give the starter. I advocate for a feeding consisting of 3 equal parts. That is, feed the starter as much water and flour as there is starter. So, if you have 40 grams of starter, feed it 40 grams of water and 40 grams of flour. While I always measure the flour and water, I generally just eyeball the amount of starter; starters are quite resilient and it is hard to kill them accidentally. Of course, this naturally leads to the starter tripling in size each feeding. To prevent this exponential growth from continuing, you will either need to discard some of the starter (giving it to friends is great) or use it to bake. Also, while any flour can be used, I generally use a 50/50 mixture of white and whole wheat flour, as recommended for Tartine’s Country Bread.
To feed the starter, first measure the water you want to use, then pour it into the starter. Stir to dissolve the starter in the water. Then add the flour and stir to combine. This method ensures equal distribution of the old starter in the new mixture.
This depends on how you want to store your starter. There are two options: At room temperature and in the refrigerator. Keeping the starter at room temperature is essential when you are going to bake with it, but for longer term storage the refrigerator is a very convenient option.
When keeping the starter at room temperature, it is important to feed it daily. Generally you can feed it either once or twice a day, depending on your preference. Twice a day feedings will keep the starter more immature and keep a lower level of lactic acid, resulting in bread that is less sour. Once a day feedings will produce a more mature, more sour bread. However, in practice the biggest differences in the characteristics of the bread will result from the recipe for the bread rather than the feeding schedule of the starter.
For longer term storage, I recommend keeping the starter in the fridge. When kept cold, the starter can easily go a week between feedings, and in fact can go much longer. If I am not baking often, I keep the starter in the fridge, once a week or whenever I remember, I take it out, feed it, and put it back in the fridge. About two days before you are ready to bake, take the starter out of the fridge, let it come to room temperature, and begin a normal once or twice a day feeding schedule. When it is active again, generally after coming to temperature and have been fed once or twice, it is ready to use.
Honestly, anything will work as long as it has a lid (to prevent the starter drying out). The most important thing is to select a large enough container, as an active starter can grow quite dramatically. I generally recommend the freshly fed starter occupy about a third of the volume of your container to allow sufficient room to grow.
Many recipes say something like, 200 grams sourdough starter “fed” or “at peak activity”. I take these to be synonyms and advise that this calls for starter that has been fed around 4 hours previously. It should have grown since then and be at a heightened state of activity and ready to leaven your bread.
Relax! Starters are remarkably resilient. If you have forgotten about your starter and not fed it for a while, it will often develop a grey layer on top and be topped with an alcoholic liquid. Your starter is still alive, just hungry. Pour of the liquid, remove the grey layer (or stir it all in, I just prefer removing it) and feed it like normal. Before giving up on a starter, always try feeding it a few times. It will almost always perk right up.
If you know you won’t be using your starter for a long time and don’t want to feed it, or, if you want to keep a backup starter in case of emergency, consider drying your starter. To do this, take some starter and spread it as thin as you can on parchment paper and leave it out till it dries! It is that simple. Once it is completely dry, break it into flakes and store it. In this state, the starter should last indefinitely, and can be revived when you are ready.
You revive your dried starter fairly easily when you are ready. Start by adding water, little by little, until you have just reconstituted the starter. Then, add a small amount (say 50 grams each) water and flour. Let it sit till it starts bubbling, probably in around 24 hours. At this point begin feeding it as usual. It will probably take a few feedings before it has reached full activity.