Substituting flour made from other grains
The higher the extraction your flour is, the more dense your bread will be because of the extra fiber from the bran and wheat germ. However, substituting some oat or spelt flour for up to one-fourth of the bread flour (hard unbleached wheat flour) will give the sourdough bread a different texture. Oat and spelt flours, for instance, tend to make the bread more soft and tender while giving it nutty overtones.
Likewise, substituting some of the Type 85 flour with flour milled from other grains, such as rye flour or buckwheat flour, will influence your bread's taste. Personally I enjoy substituting about one-fourth of the Type 85 flour with rye and/or buckwheat flour to give my bread a flavor that has more depth.
While buckwheat and oat flours are gluten free, spelt and rye flours contain some gluten, yet less than in wheat flour. As flours containing no or little gluten reduce the rise and elasticity of your bread, I recommend substituting only up to one-fourth of the total wheat flour indicated in the recipe with flour made from other grains.
Use this recipe as a starting point to practice your bread-making skills. Later, maintain the same general proportions when substituting in other flours to try new combinations. You might need a little more or less flour than indicated in the recipe, depending on the humidity in the room and in the flour. After making bread a couple times, you'll develop an instinct to know how hydrated you want your dough.
Time and Patience will Improve Your Sourdough Bread
Waiting patiently during the entire bread-making process will probably be your hardest task. This recipe requires between 24 and 36 hours from start to finish. However, you will only need to work about 30 to 40 minutes of this time to produce a full-flavored and super tasty sourdough bread. You might want to skip steps or shorten the time needed for fermentation or a rise, but please resist.
The longer the dough ferments, the more complex and sour your bread's flavor will be. Be careful though not to let the dough ferment or proof too much time. Otherwise your bread might become flat when baked, as it won't have the spring necessary to rise a last time in the oven. In short, as long as your dough is hungry it will continue to ferment and grow in flavor and size. When it stops feeding, it will become less active and more lethargic. There is, therefore, a limit on how long your dough can ferment or proof without needing to be fed more flour and water. Remember your dough is alive and will only stop its activity when baked in the oven.
If you start making sourdough bread on a regular basis, you will not even think about the time it takes. For instance, you will create your sponge (the first mixing of the sourdough starter with water and flour) before going to bed. Then you will knead in more flour and salt in the morning before leaving the newly formed dough to rise for the bulk fermentation (first rise). Later in the afternoon or early evening you will shape and proof your bread (second rise) a couple hours before putting your dough in the refrigerator to ferment slowly overnight. The next morning you will bake your dough in the oven.
Below is a timetable for the entire sourdough bread-making process.