Yeast are a living organism that is used in baking to make dough rise. There are different type of yeast, and different type of yeast require different preparation methods. If you use the wrong type of yeast or use the wrong amount of yeast, your dough may not rise correct.
Because yeast is a living organism, the temperature of your water and the amount of sugar in your dough will affect how the yeast function. Most yeast found in grocery stores is either instant yeast or active dry yeast. Instant yeast is a fine granule, and because instant yeast is a fine granule, you can mix instant yeast direct into dry flour.
Different Types of Yeast and How to Use Them
Active dry yeast is different because a layer of dead cell covers active dry yeast. Because a layer of dead cell covers active dry yeast, you must dissolve active dry yeast in warm water to perform a process called proofing. Proofing is the process of dissolving yeast in water to ensure the yeast is alive before you add the yeast to the flour.
Fresh yeast is another type of yeast that come in moist, compressed block. Fresh yeast often provides a more stronger rise then instant yeast or active dry yeast, but fresh yeast has a shorter shelf life then instant yeast or active dry yeast. You cannot always replace one type of yeast with another using a one to one ratio.
Because the density and the cellular activity of yeast vary, the amount of yeast you use must change when you switch between yeast type. For example, fresh yeast is more concentrated than instant yeast, so you must use less fresh yeast if you are substituting fresh yeast with instant yeast. If you use too much yeast, the dough may rise too quick and then collapse.
If you use too little yeast, the dough will not rise. You must follow specific conversion ratio to ensure the yeast provides a consistent lift to the dough. Temperature is a vital factor in how yeast function in the dough.
If the water you use is too hot, the heat will kill the yeast, and killed yeast cannot make the dough rise. If the water is too cold, the yeast will not become active quick. Many people use warm water to ensure the yeast become active.
Additionally, the temperature of the room affect the yeast. A cold room will cause the yeast to work slow, and a warm room will cause the yeast to work quick. The speed of the yeast also affect the flavor of the bread.
Rapid-rise yeast is designed to make dough rise quick, but rapid-rise yeast does not always produce a deep flavor. Many breads require a slow fermentation process to develop flavor. Slow fermentation occur when you let the dough sit for a long period, such as in a refrigerator.
When you use a slow fermentation process, the yeast works slow, and the slow work of the yeast develop complex flavors in the bread. Sugar can also affect how yeast work in the dough. Some doughs, such as brioche, are enriched doughs that contain high amount of sugar, butter, and eggs.
Sugar can cause osmotic pressure, and osmotic pressure can dehydrate yeast cell. If you are making an enriched dough, you may need to use osmotolerant yeast. Osmotolerant yeast is a specific type of yeast that is bred to work in environment that contain high amount of sugar.
If your enriched dough does not rise, you may need to use osmotolerant yeast instead of standard yeast. If your dough does not rise, you should of checked the expiration date of your yeast. You should also check the temperature of your water.
If your bread have an intense flavor, you may have used too much yeast or you may have allowed the yeast to proof for too long. By understanding the different types of yeast and the specific need of yeast, you can manage the baking process more effective.