Bakers Journal

The Final Proof: July 2013

June 24, 2013
By Jane Dummer RD

The art and science behind culinary’s coveted San Francisco sourdough bread

The art and science behind culinary’s coveted San Francisco sourdough bread

I recently attended my first International Association of Culinary Professionals (IACP) conference. The fact that the host city was San Francisco made the conference extra special, since it’s one of my favourite culinary cities in the world. San Francisco is famously known for sourdough bread. I wanted to get the facts about this culinary claim to fame. At the conference, I learned this and other fascinating information while sampling many types of sourdough bread. The most interesting conference session was “San Francisco Sourdough: Is Our Iconic Bread a Myth?” The panellists were well chosen and very interesting: Dr. Dusty Dowse, Bread Biologist (I didn’t know there was such a title) from the University of Maine; Chad Robertson, author, baker/owner, Tartine Bakery (whom I interviewed the following day at his bakery for this column) and Steve Sullivan, Founder, Acme Bread Company.

Let’s start with a bit of sourdough science. Sourdough is characterized by a complex microbial ecosystem, mainly represented by lactic acid bacteria and yeasts, whose fermentation gives the resulting bread its characteristic features including taste, aroma and palatability. The microbial composition of sourdough depends on the ecosystem and is relevant in determining the final bake.

San Francisco sourdough style was born during the Gold Rush in the 1840s. Gold was discovered in 1848 and in one year San Francisco’s population swelled to 20,000. The story portrays bakers not having access to fresh supplies of yeast and thus having to rely on a natural, San Francisco levain. I heard the term “levain” was often interchanged with the term sourdough “starter” when I was in San Francisco. The definition I received during the Boudin Sourdough Museum tour is that levain, or starter, is a mixture of wild yeast and a specific strain or strains of the Lactobacillus genus, a formula that dates back to the Egyptians more than 6,000 years ago. We can thank the Gold Rush for this culinary gold. The Boudin family used the levain, a favourite among the miners, with its traditional French bread recipe and established a bakery in 1849. Within a year, there were lineups each morning for a fresh baked loaf of sourdough French bread.

The folks at Boudin claim that they have kept the mother dough (or starter, or levain) alive for more than 150 years. The “mother dough” invariably took on distinct microflora characteristics as the Lactobacillus in the grain itself responded to the perfect local San Fran climate. This allowed some strains to become more dominant than others.

This resulted in a particularly pleasing and tangy flavour that has made San Francisco sourdough bread renowned.  Today the Boudin mother dough is stored in a refrigerator-retarded vault to allow the Lactobacillus strains to ferment the dough. Bakers remove a portion of the starter each day for the bread being baked. They replenish the remaining mother dough supply with flour and water, which “feeds” the starter.

The lineups at Tartine Bakery in San Francisco’s Mission District are the talk of the culinary scene today. Chad Robertson and his wife Elisabeth Prueitt are co-owners of the bakery. Using art and science, Robertson developed his unique bread over two decades of apprenticeship with the finest artisan bakers in France and the United States, as well as experimentation in his own ovens.

When Robertson was first crafting his sourdough breads in the 1990s and selling them at local markets in California, people thought the bread was burnt. This is called the “dark bake,” an art Robertson has perfected. At first, people asked him why he was creating it that way and now Robertson is world famous for instructing other bakers about the techniques leading to the beautiful dark bake.

I met Robertson at the bakery around 5 p.m. on my second last day in San Francisco. When I arrived he was working on his third book, Tartine Bread Three. The bakery was very busy and was in the process of making the infamous dark bake sourdough loaves: “fresh bread for dinner, toast for breakfast.” Robertson explains: “The dark bake is a result of the carmelization of the sugars. The sugars are broken down by the fermentation process during the long rise before the loaves hit the heat of the oven.” 

The bread smelled amazing, tasted delicious and the texture is what I found unique and very appealing. It has a distinct “chew,” not a Montreal bagel or pretzel chew, but less and this mouthfeel is unlike any other food experience I have had. When I asked what he was experimenting with, Robertson says, “I have been using a variety of sprouted grains and they are working very well with the sourdough recipe.”

Although bakers from around the globe have tried to duplicate the tangy San Francisco sourdough, their atmospheric conditions are not the same. Their local ecosystem produces an entirely different flavour, which is why many people (including me) agree that San Francisco sourdough is the best. 

Jane Dummer, RD, is a leading dietitian for the Canadian food and nutrition industry. Jane offers services specializing in agri-food, functional foods and food safety. For more information, visit

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