Read any number of baking forums that discuss baking sourdough bread and you might get the idea that keeping a sourdough starter is rather like keeping a pet. Granted, it takes far less care than a cat, and far more than a pet rock. A gold fish, perhaps. A gold fish that, inevitably, once you’ve fed and tended it for awhile, you’ll eventually bake up and eat. Disturbing as that may seem, it still doesn’t change the fact that plenty of bakers actually refer to their starters with pet names. Maybe we’ve just been inhaling too much flour.
The pet metaphor really isn’t such a far stretch. Sourdough starter is comprised of yeast, which actually belongs to the fungi family, and lactobacillus bacteria. The lactobacillus provides the sour tang while the gasses given off by yeast as they digest the carbohydrates in flour provide the leavening action for bread. Both are living organisms that require fresh food and water on a regular basis. How often they require these things depends upon temperature and your personal collection of little beasties. Typically a starter that is kept on the counter will need to be fed daily, if not twice daily. Some bakers really go wild and feed their starter three times a day. A starter kept in the fridge can go a week or more, and one that has been frozen can go for a long time without care, indeed.
I keep my starter in the refrigerator when I am not planning to bake for a week or more. I feed it, give it a short rest of an hour or so on the counter, and then toss it in. I take it out about two days before I’m ready to bake and feed it once. Half goes back in the refrigerator for safe keeping and half remains on the counter to be built up into the amount of starter that I need for whatever I’m baking.
The starter to the left was fed about 12 hours ago. It is full of bubbles and has risen in its container. This means it is starting to run out of food, and it is time to feed it. If I had wanted to use it, it would have been best used at about the 8 hour mark, when it was at the peak of activity.
Whenever you feed your starter you want to double the amount that you currently have. In the case of a liquid, 100% hydration starter, that means combining old starter, flour, and water in equal amounts. The best way to do this is to weigh your ingredients. To avoid ending up with exponentially larger amounts of starter you can keep a portion and either discard the rest or give it to a friend. Here, I kept 3 ounces of my ripe starter.
To my starter I added 3oz of water and 3oz of flour. It is important to weigh your ingredients in order to maintain the proper percentage of hydration. If you add 1 cup of water and 1 cup of flour, you are actually making a roughly 50% hydration starter, which is much thicker and which will act differently in recipes. Some recipes do start with a lower-hydration “firm” starter, but I find that the liquid starter is easier for me, personally, to work with and I can always change the hydration as I elaborate (feed and increase its volume) it before using.
As an important note, make sure you use a big enough container for your starter. You want a container that is at least three, and preferably four, times the volume of the starter you wish to maintain. As a starter ripens it will double, and sometimes triple in size. I have had my starter crest the top of my container once, and on another occasion it was particularly active and pushed its lid off before oozing all over the counter. Speaking of lids, be sure to vent your lid if you are leaving it on the counter. I usually just rest my lid loosely on top, but you can also cover your container with cheesecloth and a rubber band or a loose covering of plastic film wrap. You want it to be able to vent the gasses it is releasing while at the same time keeping it from drying out too much or having things fall in. Scrape down the sides of your container after mixing to keep smeared portions from drying out.
Most importantly, keep in mind that you are creating a choice environment for bacteria – make sure everything you are using is in pristinely clean condition so as to not inoculate your starter with something you don’t want. A healthy, uncontaminated starter should smell sour, with a hint of beer-like odor. The smell will be considerably stronger with a rye starter. It is not unusual for starter to separate into a flour paste and a liquid “hooch” if it hasn’t been fed recently, don’t worry. Just stir it all together, discard half and feed the other half.
As you can see a freshly fed starter has a distinctly different texture than ripe starter. It is somewhat more past-like. This is even pronounced with a rye starter. As a white flour starter ripens it changes texture. It becomes more glossy looking and thins out. The gluten strands form, even without kneading, and it becomes stretchy. The texture of a rye starter is different. Due to its density the bubbles may not reach the top, which does smooth out some, but not as much as a white flour starter. Rather than becoming more elastic, my rye starter tends to become “fluffy” and you can hear bubbles popping when it is stirred.
In addition to being kept on the counter, in the refrigerator, or frozen starter can also be dried. You can buy packets of dried starter from many retailers. Eric over at Breadtopia.com has an excellent video on how to dry your starter.