Since California’s gold mining days, sourdough has been a Western staple, delighting generations with its tangy flavor in breads, pancakes, and other baked foods. The West didn’t invent sourdough, of course. This style of baking goes back to the ancient Egyptians, and Europeans have baked with sourdough starters for centuries.
How sourdough works
A sourdough starter is a portion of dough that is allowed to ferment. When this happens, the wild yeast and bacteria in the flour, in the liquid, and even in the air break down natural sugars and produce carbon dioxide, which enables bread baked with the starter to rise. As it ferments, the starter also produces acidity—in the form of lactic acid and some acetic acid—creating the “sour” in sourdough.
Starters vary from place to place (because wild yeasts are different everywhere) and baker to baker. The ones that developed in the San Francisco area were uniquely sour. In fact, the bacterial strain that’s responsible for that sour flavor was eventually identified and named Lactobacillus sanfranciscensis in honor of San Francisco.
Once established, a starter can be kept going for decades. Boudin Bakery, founded in San Francisco in 1849 and still operating, traces its sourdough starter to one begun more than 150 years ago by Isidore Boudin. (The Boudin starter was borrowed, so the story goes, from one of the actual “sourdoughs”—the name given to gold miners because they relied so heavily on sourdough starters for bread baking out in the gold fields.)
A bread revolution
In the 1980s, sourdough helped fire up an artisanal bread–making revolution when Steve Sullivan and his wife, Susie, founded Acme Bread Company in Berkeley, California; to create the leavener for their levain bread, which sets the standard for artisan-style bread in America, he created a starter inoculated with wild yeast from wine grapes.
Sourdough has been a standby at Sunset since 1933, when we published the first recipes. However, we discovered that capturing the right bacteria and yeasts to establish a good starter can be hit or miss—some mixtures never fermented at all, while others were weak or inconsistent. In 1973, staff food writer Kandace Reeves, working with microbiologist Dr. George K. York from the University of California, Davis, finally hit upon a truly dependable starter using yogurt.
Sunset’s reliable sourdough starter
Use this starter to make Sunset's Centennial Sourdough bread, or for any favorite sourdough bread recipe.
As with a classic starter, ours ferments flour and liquid—milk, in this case—with some yogurt, already packed with helpful bacteria to get things off to a good beginning. Yogurt also produces a very active, bubbly starter and gives a wonderful zesty flavor to the bread. After a few days’ incubation in a warm place, the bacteria multiply to break down sugars in the flour and milk and give the characteristic sour smell and tang, and the starter is ready to use. Despite its terrific souring qualities, yogurt-based starters don’t always have a reliable yeast component (their high levels of acidity can inhibit yeast’s gas production), so we add dry yeast when baking. For best results, use milk (nonfat or low-fat for tangiest flavor) and yogurt that are as fresh as possible (check the sell-by date) and use them right after opening.
Makes: About 1 1/3 cups starter | Time: 1 week
- 1 cup nonfat or low-fat milk
- 3 tbsp. plain yogurt (any fat level; use a brand with live cultures and no gelatin)
- 1 cup all-purpose or bread flour
- In a 1-qt. pan over medium heat, heat milk to 90° to 100°. Remove from heat and stir in yogurt. Pour into a warm 3- to 6-cup container with a tight lid.
- Cover and let stand in a warm (80° to 90°) place until mixture is consistency of yogurt, a curd has formed, and mixture doesn’t flow readily when container is tilted. (It may also form smaller curds suspended in clear liquid.) The process takes 18 to 24 hours. If some clear liquid has risen to the top of the milk during this time, stir it back in. If liquid has turned light pink, discard batch and start again.
- Once curd has formed, stir in flour until smooth. Cover tightly and let stand in a warm place until mixture is full of bubbles and has a good sour smell, 2 to 5 days. Again, if clear liquid forms during this time, stir it back into starter. If liquid turns pink, start over. To store, cover and refrigerate.