Sourdough Bread
All bread is 100% sourdough
Sourdough is not just a flavor of bread, like cinnamon raisin. Instead it is one of the ways of leavening dough. In baking there are various ways to get dough to rise: whipped eggwhites, baking soda and acid, commercial yeast, and various more uncommon others. The sourdough process is the oldest process of them all, this has been done since the early days of humanity.
Sourdough yeast is local
Instead of a single strain of yeast sold in the little yellow packets or jars in grocery stores, sourdough yeast is floating around in the air in small quantities. When flour and water are mixed, this creates a surface for the native yeast air particles to land on, and start to enjoy the starches produced. They reproduce and all of a sudden, a sourdough starter is born. Refreshing the starter - or “feeding” it - with equal parts flour and water gives the existing yeast a fresh new plate of food (starch) to enjoy. Once the starter is packed with the native yeast, it can be mixed with a larger quantity of flour and water to produce the final bread dough. This dough is finally put in the oven, where the yeast goes into overdrive, and allows the dough to rise into the final bread loaf.
Water changes the bread
The basic difference between focaccia, italian bread, baguettes, bagels, and country style loaves is the amount of water used in the dough. Baker’s math gives a clear distinction between the above bread styles, and also makes scaling recipes simple. Everything is done by fraction to give a percent. For example, water: the baker’s percent of water is called the hydration of a dough. This is denoted by the weight of the water divided by the weight of the flour. A bagel, which is typically a 55% hydration dough, can be shown as 55g of water / 100g of flour. On the other end of the spectrum is usually focaccia, which can be as high as 90% hydration (90g water / 100g flour). The higher the hydration, the faster the sourdough is ready to bake, but also the harder it is to handle.
Seasonality effects sourdough
Temperature and humidity massively effects the sourdough starter. Hot and humid weather speeds up the development of the starter, and cold and dry weather slows down the development. In the winter, sometimes it takes my sourdough over twelve hours to rise enough to be ready to bake. In the summer, it has been as fast as three hours. Since the yeast is different in every corner of the world, there are no cookie-cutter recipes with standardized timing. This means that the sourdough is only ready when it feels ready, when it feels light and pillow-like. It takes lots of practice to develop a feel for the dough.