Sourdough bread presents some unique difficulties (and excitement!) when compared to other forms of baking. I’ve often heard that, while cooks can get away with variances in ingredients without too much difficulty, baking commands a higher level of precision. With sourdough, the idea of attempting to be precise, and make everything as perfect and reproducible as possible, begins to fall apart.

The Difference With Sourdough

Sourdough is much more difficult to control than other forms of baking, because there are simply too many factors at play. Though many baked goods require some sort of leavening agent, which creates air pockets in the dough and allows it to rise, sourdough gets that leavening agent from the surrounding environment and not the shelves of a supermarket.

You begin by mixing flour and water together and allowing it to sit out and ferment (there are more details, but I won’t go into them here). This mixture naturally attracts yeast and bacteria from the surrounding air, which colonize it. These bacteria and yeast form a symbiotic relationship in the flour and water mixture. The bacteria creates carbon dioxide, which leavens the bread, as well as an acidic environment that causes a sour taste and favors only a few specific types of yeast that can tolerate it. The yeast, in return, produces additional carbon dioxide and does not digest the starch sugar maltose, which is essential to the bacteria. Though some yeasts and bacteria are most commonly found in sourdough starter (Candida milleri and Lactobacillus sanfranciscenis, respectively), it’s possible for new species to show up, since starters are exposed to their surroundings. Furthermore, since the life cycle of these tiny single-celled organisms is only a few days, they can evolve quickly to produce a starter uniquely suited to its surrounding environment—and which produces unique flavors. The longer you use a starter, and the more times you bake with it, the better suited it will be to its environment.1

Most breads, by contrast, are leavened with commercial yeast (Saccharomyces cerevisiae). This produces a strong, consistent rise, and is more easily controlled because it is guaranteed to be the same species every time. However, since it’s not a symbiotic colony of different living things, it does not produce nearly as much interesting or unique taste as a sourdough culture. For instance, one simple sourdough loaf is ‘“made of unbleached flour, water, and salt. Three ingredients, lots of taste, great texture.” Yet a typical supermarket white bread has more than 25 ingredients and additives and still tastes vapid.’2 This perfectly illustrates the deceptive complexity of the cultures in a sourdough starter: just flour, water, and time allow Mother Nature to take over and produce amazing varieties of complex and interesting flavors.

More of An Art Than A Science

When I first starting baking bread here in Rome, I was determined to try and document everything, measure my ingredients as closely as possible, and try to control everything that I could between each of my loaves, only changing one variable at a time and observing how that changed the loaf. But eventually I began to realize that, with sourdough, there was far too much at play for me to possibly play dictator for each loaf I made. Temperature variations, different feeding times, drafts, fermenting during the day vs. at night, slight variations in hydration levels, different amounts of starter due to the difficulties in measuring by volume, etc., all contributed to making the role of puppet master virtually impossible. So I grew to enjoy the idea of just feeling it out, and letting the dough dictate what I did, rather than trying to orchestrate everything down to the gram and minute.

The unique variety of bacteria and yeast inside of each starter means that working with a starter is an entirely different experience than most baking endeavors. Following recipes, and executing them well, isn’t necessarily good enough to get good results with sourdough. You need to develop a feel for your starter and understand when it’s ready to go. By capturing it at different stages in the lifecycle, you can obtain different flavors in your bread. Sourdough that has been left out without being fed for a long time will have consumed most of the sugars, and produced more acid, creating a more sour taste. Conversely, well-fed sourdough will be less sour because the ratio of sugars to acids is higher.

Experimentation will help you to get a better feel for this, but because of the diversity of the live cultures, it’s likely that your results will never be completely consistent. But I think that’s really the beauty of sourdough—it forces us to let go of the idea that we can control every aspect of baking. In a way, it’s incredibly freeing to know that there’s too much going on for us to possibly keep track of. There will always be a sort of “wildcard” with sourdough. Which is part of what makes it fun :)

Now it’s time to go out and bake some bread! Don’t concern yourself too much with the details of recipes: learn how the dough should feel when it’s properly kneaded, how the sourdough should smell and look (and taste, if you’re feeling brave) when it’s ready. Remember, this process largely depends on your environment, so it will be a little different for everyone. I promise it’s not nearly as daunting as it seems.


1 Fun fact: yeast are not bacteria; they’re actually single-celled eukaryotes, which means that they contains a nucleus (just like the cells inside you and me!)

2 http://discovermagazine.com/2003/sep/featscienceof