Once a starter is reliable, the next question is how to maintain it. The three guidelines apply here. Almost all the questions I get about starter failures can be traced to a failure to follow the three guidelines. In case you missed the other pages they are on, here they are again:
- Sourdough starter at room temperature must be fed no less than twice a day. If you feed it less than twice a day, it will lose vitality and eventually become useless and die.
- Each feeding of the starter adds volume to the starter, doubling it.
- Each feeding should be equal amounts of water and flour, by weight. You can use about 2 parts of water to 3 parts of flour by volume as an approximation.
To expand on these a bit, the first thing to remember is that a starter is a living thing. It needs to be fed and cared for regularly. Some people ask, if once their starter can double itself between feedings can they stop feeding it. All I can ask is do they stop feeding their dog once it learns to sit, stay, and fetch?
As many readers of this site know, for a few years I owned a bakery. First the Colorado High Attitude Bakery and then Mike's Bread. Before, during, and after this I've been a member of the Bread Bakers Guild of America. Through the Guild, I've been in contact with many other bakers. The information I am sharing here is based on my experience, information from people who have written me through this page, and from the world-class bakers in the Guild.
The short answer is, a starter at room temperature needs to be fed no less than twice a day, and with each feeding half of the starter is discarded and the remaining portion fed its weight in food. (For instance, keep 100 g of starter and feed it 50 g of flour and 50 g of water.)
Bakers are divided about how thick a starter should be. Some bakers like a very thin and watery starter. However, a thin starter doesn't have enough strength to rise on its own, which is a very important indicator of starter vitality for the beginning sourdough baker. Also, a thin starter works too quickly, so a few missed feedings can be catastrophic. Many bakers use a very thick starter, thick like caulking compound or window glazer's putty. These starters seem to develop more flavor, have more strength, are more active than a thinner starter and are much more tolerant of a missed feeding. However, I find that a very thick starter is difficult for new bakers to work with. So, the compromise is to feed the starter equal amounts of water and flour, by weight. This starter is thick enough to rise and also has good flavor and strength. It makes a good starter. As you gain experience, you may want to experiment with thicker or thinner starters.
What's a feeding? If you have 100 grams of starter, adding 50 grams of water and 50 grams of flour. To 1/2 cup of starter, I would add 1/4 cup of water and about 1/2 cup of flour that has been sifted and spooned into the half cup measure. Remember, flour scooped from the sack yields heavier cups, or half cups. If your starter is too thin, you might increase that amount by a few tablespoons. It REALLY is easier to weigh your ingredients than to fret about whether you have a light or heavy cup, or to sift and spoon your flour.
Many bakers have tried to feed their starters less than twice a day. They can tell you how easy it is to start a starter, and know many ways to start a starter. All in all, I think it is better to maintain a good starter than to become too versed in the many ways to start and salvage starters.
All the professional bakers I know feed their starters at least twice a day. All the bakers I know base the amount the feed their starter on the size of the starter. All of the professional bakers I know have a fixed ratio of flour to water that they feed their starters. And, that's what you should do as well.