I love to bake bread. It can be a messy process, requires a lot of patience, and rarely results in bread as good as what Bay Area bread wizards like Acme and Vital Vittles sell at many nearby markets. But that's OK with me — the process is as important as the product. Bread making can be nearly magical: the transformation of inert ingredients (flour, water, dry yeast) into something that is alive; the initial filling of the kitchen with the light aroma of yeasty dough; the intoxicating smell of baking bread; and finally the aroma, texture, and taste of the finished loaf.
Except for a short and ultimately ill-fated fling with a sourdough starter many years ago, I have exclusively used commercial yeast in my bread baking. It's predictable, requires no tending, and can sit in the freezer for a long, long time: I think I had one package of instant yeast in there for five years. In contrast, sourdough starters require care and feeding. They can behave surprisingly, and the yeasts can die or be overrun by the wrong sort of bacteria.
A starter is a living thing, a complex community of yeasts and bacteria (the "microflora"). The bacteria produce many acids, especially the acetic kind (found in vinegar) and lactic (found in yogurt); the yeasts have evolved to live in the resulting acidic environment. Different bread-making techniques can raise or lower the quantities of the different acids, resulting in significantly varied flavor profiles. One type of starter and a certain set of rising conditions will favor lactic acid formation, resulting in a mild-tasting bread. A different starter and rising conditions might create a very sour bread like the classic San Francisco sourdough.
Sourdough starters have special properties that make the trouble worthwhile, such as an ability to survive for a long time at a relatively low temperature. They can also work slowly — eight or 16 hours instead of one or two — which is desirable because time creates flavor: the longer the bread rises, the more complex the flavor.
Beyond the ability to have long rising times, a sourdough starter has other benefits. According to the sourdough bread entry in the "Encyclopedia of Food Sciences and Nutrition," the acids produced by the bacteria in the starter affect the proteins in the flour, giving the dough better elasticity and extensibility. (This is one reason why many breads made from rye — a grain with relatively low protein content — use sourdough starters.) The lactic and acetic acids produced by the starter might act as antimicrobial agents and inhibit the growth of mold. There is also the possibility that it takes longer for a sourdough loaf to go stale.
Capturing wild yeast
Making a starter from wild yeasts is not too difficult. One way is to mix organic grapes with organic flour and water. Grapes have yeast colonies living on their skin (that's one reason we have wine), and these yeasts can be encouraged to multiply by holding the mixture within the right temperature range and providing food (flour) at regular intervals. Another way involves mixing water and flour, then leaving the container on a window sill, covered with a cloth to keep out insects. If conditions are right, yeasts that drift around in the air and those in the flour will create a stable colony. Other methods involve lumps of dough or yogurt.
An even simpler — and far quicker — method is to find someone who already has a starter and get some of that.
I used the simple method, obtaining a cup of starter from Dylan the Sourdough Monkey Wrangler. Dylan was one of the presenters at a "skill share" about fermentation that was organized by local food-activist Karmin and SAFE, a UC Berkeley student group. These are informal meetings in which community members give short presentations about a particular subject, like how to make a dosa (a South Indian crepe-like delicacy), how to make the Russian fermented beverage called kvass, and so on.
During his presentation, Dylan said that his starter was made from wild-caught yeast, and so there is a chance that it is the famous San Francisco Sourdough mixture.
Maintaining the starter
A starter can be maintained or preserved in several ways. If you bake very frequently, you can keep a starter going at room temperature with regular feedings (a feeding involves mixing a portion of the starter with flour and water). For a less active (and less expensive) approach, the starter can go into the refrigerator, where its metabolism slows down significantly. It then requires feedings about once a week. For even longer-term storage, the starter can be dried out and stored in that form at room temperature more or less indefinitely. To reactivate, simply dissolve it in cool water, then feed it with water and flour for a few days to bring it back to full activity.
Starters can last a long, long time. Last year, the Accidental Hedonist related the amazing story of Carl Griffith's sourdough starter. The starter dates back to before 1847, around which time it traveled west with his ancestors on the Oregon Trail. For many years of his life, Carl shared the starter with anyone who asked, even setting up an informal mail order system, which eventually resulted in the starter being sent to every continent but Antarctica. Since his death in 2000, a group of people have carried on the tradition.
Ethicurean readers who have dabbled in sourdough, we'd appreciate if you could tell us your favorite books, websites, or tips on the subject.
In part 2, I'll show how I used the starter to make the beautiful and great tasting loaves shown in this post.