For thousands of years, bakers had two choices when it came to getting their bread to rise. They could either use the barm that floated to the top of a vat of brewing ale, which contained lots of active yeast cells, or they could create a culture that preserved the yeast between one batch of dough and the next. Some systems used what is called a levain, a lump of dough preserved by covering it with salt. Others used a wet culture, what we now call sourdough.In most countries, traditional sourdough bread never went out of style. France is famous for its sourdough boules, full of rich tangy flavor. Germany, Poland and other Eastern European countries use sourdough to make dense, chewy rye bread, because their climate is less conducive to farming wheat than warmer places. In San Francisco, home of Lactobacillus sanfranciscensis, the bacteria that gives the local sourdough its unique and delicious flavor, sourdough never went out of style. It was part of their colorful local history and a great way to sell pricy bread to tourists. It also goes really, really well with cioppino.Sourdough was the bread of the 49ers, the people who rushed to the west coast in a mad scramble when gold was discovered. They went out into some wild country, with no access to bakeries or stores, so they brought their sourdough cultures with them to bake bread. A crock of sourdough culture had another advantage. Leave it alone for a while and it develops a layer of hooch on the top. When yeast eats carbohydrates, it produces alcohol as a byproduct. Most bakers either stir it back into the culture or pour it off before refreshing their sourdough. The 49ers drank theirs.Bread in America got really depressing for a while. The discovery of industrial processes to speed up production, the substitution of refined white flour for wholesome, wholemeal breads, the ease of opening a packet of activated dry yeast from the supermarket if you were unusual enough to be baking bread at home, all led to the death of sourdough after World War II. There was a huge uptick in mass produced, packaged food of all kinds, and only a few people preserved the skill, the information and the actual cultures used to make sourdough. The convenience of sliced bread sold in plastic bags trumped the sometimes days long process of making good sourdough bread.Fortunately for us, there was a core of serious bakers, hardcore hobbyists, and just plain home cooks who held onto the knowledge and kept on making bread the way it's supposed to be made. Also fortunately, sourdough is, well not exactly easy, but accessible. Everywhere on the planet, there is wild yeast and lactobacillus bacteria in the air and on surfaces. Well, maybe not in Antarctica. Yeast is on the surface of almost every plant.Then in the fifties and sixties, people began to rediscover good bread. Nobody was using the word artisanal back then, it was all about hippies and organic farming and whole grains instead of refined, white flour. We had a food revolution that match the social revolution. All those people who had kept the sourdough tradition alive found that there were other people doing the same thing, and they started talking to each other.
