In most supermarkets, you will typically find three main types of yeast: active dry yeast, instant yeast (also known as rapid-rise or quick-rise yeast), and fresh yeast (also known as cake yeast). These yeasts differ in their composition, handling requirements, and how they are used in bread baking. Here's a breakdown of the differences:
Active Dry Yeast:
- Composition: Active dry yeast is composed of granules that are coated with a layer of dead yeast cells and other drying agents. It has a dormant state and needs to be rehydrated before use.
- Handling: Active dry yeast requires proofing, which involves dissolving it in warm water (around 105-110°F or 40-43°C) along with a small amount of sugar. This step allows the yeast to activate and begin fermenting before incorporating it into the dough.
- Usage: Active dry yeast is suitable for most bread recipes and is widely available. It has a longer shelf life than fresh yeast and can be stored at room temperature.
Instant Yeast (Rapid-Rise or Quick-Rise Yeast):
- Composition: Instant yeast is also made up of granules, but it is formulated to have a higher concentration of live yeast cells and fewer inactive or dead cells. It does not require proofing and can be added directly to the dry ingredients.
- Handling: Instant yeast can be added directly to the flour and other dry ingredients in your recipe. It activates quickly and starts fermenting when it comes into contact with the moisture in the dough.
- Usage: Instant yeast is particularly convenient for bread recipes that require a shorter rise time. It can be used interchangeably with active dry yeast, but the rising times may need to be adjusted. It has a longer shelf life than fresh yeast and can be stored at room temperature.
Fresh Yeast (Cake Yeast):
- Composition: Fresh yeast is a moist and perishable form of yeast. It is composed of live yeast cells and has the highest moisture content among the three types.
- Handling: Fresh yeast should be crumbled or dissolved in warm water to create a slurry before incorporating it into the dough. It requires careful handling and has a shorter shelf life than dry yeasts. It needs to be stored in the refrigerator.
- Usage: Fresh yeast is commonly used in professional bakeries and certain traditional bread recipes. It has a faster fermentation rate compared to dry yeasts, and some bakers believe it provides a distinct flavor and texture to the bread.
When substituting one type of yeast for another, it's essential to consider the different fermentation rates and adjust the rising times accordingly. Always follow the specific instructions in your recipe, as the yeast type specified will guide the rising times and techniques needed for optimal results.