The chef is an important step in the baking of all sourdough breads. It is a collection of wild yeasts gathered by setting out a flour and water mixture to ferment. This fermented mixture is known as the chef, starter, sponge, or poolish, depending on regional preferences. Pieces of the mixture are used to make loaves of bread, while the remainder is fed to keep the yeast colony alive. Some bakeries have been using the same chef for their sourdough breads for hundreds of years, producing consistent and sometimes famous sourdough bread.
Most leavened breads use yeast as a leavener. As yeast feeds on the starches and sugars in the bread dough, it creates carbon dioxide as a byproduct, causing the bread to rise. This rise makes the bread light and fluffy, rather than heavy or blocklike. A chef attracts wild yeast unique to the region in which it is cultured. It also encourages the growth of beneficial bacteria, which give sourdough and other breads made from a starter their characteristic soured flavor.
Making a chef sometimes requires a few false starts, and it may take several baking attempts to produce successful sourdough bread. Bakers should not give up, however, as homemade sourdough has a unique and wonderful flavor, and it is rather exciting to think of making bread from local wild yeasts.
Chefs start with flour and water mixed together to form a stiff dough or a batter, depending on regional preference. A half cup of flour and a half cup of water is a basic base, with equal amounts of flour and water being added periodically to feed the chef. Many people prefer to use organic whole wheat or rye flours, since they tend to harbor more wild yeasts. Others also add things like fruit, to encourage the chef to ferment more quickly and develop a unique flavor. Grapes and apples are two common choices of fruit.
After making the basic mixture, the substance is placed into a bowl and covered in a cloth. It should be left in a warm place, usually around 85 degrees Fahrenheit (29 degrees Celsius) until it starts to bubble, at which point more flour and water are added to feed the yeasts. Depending on regional yeast populations, the chef may bubble anywhere between eight hours and several days. It may smell a bit peculiar at this stage, but do not be concerned.
For approximately four days after the first feeding, the mixture should be fed again every eight to 12 hours. It will start to smell rich, wholesome, and yeasty, at which point it can be used to make bread. A portion of the chef, usually around one cup, is broken off and used in the bread dough, while the rest is saved. The chef needs to be fed to stay alive, and many cooks keep it under refrigeration, which slows the growth without killing it. It tends to be the most healthy when it is used and refreshed frequently, which requires frequent baking.