There is a lot of confusion about what sourdough bread is. Is it bread with a sour taste? Do they only make it in San Francisco? What makes it so different?
Sourdough bread is bread that is leavened using a sourdough culture containing wild yeasts and bacteria. The yeast that can be bought in small packages and jars at the store is commercial yeast . It is one strain of yeast, raised because it is really great for making bread quickly consistently. A sourdough culture will probably contain many different strains of yeast, and several types of bacteria. While an envelope of commercial yeast is innumerable copies of one organism, a sourdough culture is a diverse ecosystem. Because of this, sourdough breads have a more complex flavor and texture than breads made with commercially available yeast.
So where does the "sour" part of sourdough come from? While yeast produce carbon dioxide and alcohol, the bacteria in a sourdough culture produce lactic acid. This give some sourdough breads their distinctive tangy taste. The increased acidity and other compounds produced by the bacteria make sourdough breads more resistant to mold and staling than other artisan breads.
Although these bacteria can make the bread tangy, not all sourdough is noticeably tangy. It depends on what bacteria are in the culture being used. However, there are methods that can create the sour flavor that some people enjoy in their bread.
Making true sourdough bread is more difficult, and more time consuming than using instant yeast. That having been said; sourdough creates loaves of bread that have a flavor that can't be matched by breads made using commercial yeast.
It is a common misconception that sourdough bread can be produced using a commercial yeast that is allowed to develop in a batter overnight. This is called a preferment, poolish , or biga . This technique can make really great breads, but it isn't true sourdough and tastes very different. Here I present sourdough bread and describe the techniques used to create it.
Step 1: Assemble Ingredients
First, assemble the ingredients.
A real sourdough loaf is surprisingly simple ingredient-wise. The quality comes from the technique. Of course, having good quality ingredients will help too.
Unbleached Bread Flour
Bread Flour - This flour is different from regular all-purpose flour in two ways. The first is that it is milled from different wheat, often harvested at a different time of the year. This wheat contains more of the compounds that will form gluten in your bread. Gluten is what makes dough stretchy and bread chewy. The second way bread flour is different is it often contains malt powder. This encourages yeast growth. Not all bread flour will contain this but most commercially-available bread flours in North America have it.
Rye Flour - This is a whole grain flour. It adds complex flavor to breads and is used to feed the starter in this recipe. Rye flour will not form gluten on its own. The more rye flour is in a bread, the more difficult it will be to form gluten while kneading.
Whole Wheat Flour-Not mentioned on the list. It is strictly optional. This is a whole grain, more flavorful flour. Some people find it bitter. Usually when I am making this bread about two cups of what I have listed here are whole wheat flour, I enjoy the flavor. It absorbs water more slowly than white flour.
I recommend practicing the recipe a few times with mostly white flour and then incorporating more whole wheat or rye flour into the recipe.
A lot of people say it is important to use spring water or filtered water or some other water, that chlorinated water will kill your yeast. I use tap water (yes it's lightly chlorinated) as do most great bakeries I know to no ill effect. If your tap water smells like a swimming pool it is probably better to use spring water or filtered water. I've never had a problem with it.
Salt is extremely important in bread. Do not omit salt based on the reasoning that it will be healthier. Not that much salt goes into bread. Salt balances the flavor of bread very nicely, if you don't add it your bread will taste strange. Salt also helps in regulating yeast growth. If you don't use salt the yeast may develop inconsistently.
As for what type of salt, I use plain free-flowing salt. Sea salt, kosher salt, Himalayan pink salt; all fine-it won't make a difference in how your bread tastes. I would save the good salt for some other application. If you do use some other type of salt, be aware that 1 Tablespoon of plain salt does not equal 1 Tablespoon of kosher salt. The larger grains change the volume. If you are going to play around with salt types use a scale to make sure it is the same amount.
This contains nothing but rye flour and water. This is all wild yeast, no stuff from the jar/packet. Don't ever add salt, sugar, pineapple juice, or anything else but flour and water to this. If you wanted, you could easily use your wheat starter for this recipe; it should work but the fermentation times may be slightly different based upon the starter you use.