Baker’s Yeast: The Magical Microorganism That Makes Bread Rise
Bread is one of the oldest and most universal foods in human history. But what makes bread so soft, fluffy, and delicious? The answer is baker’s yeast, a type of fungus that feeds on sugars and produces carbon dioxide and alcohol. In this article, we will explore what baker’s yeast is, how it works, and where to find it.
What is baker’s yeast?
Baker’s yeast is the common name for the strains of yeast commonly used in baking bread and other bakery products, serving as a leavening agent which causes the bread to rise (expand and become lighter and softer) by converting the fermentable sugars present in the dough into carbon dioxide and ethanol. Baker’s yeast is of the species Saccharomyces cerevisiae, and is the same species (but a different strain) as the kind commonly used in alcoholic fermentation, which is called brewer’s yeast or the deactivated form nutritional yeast.
How does baker’s yeast work in baking?
S. cerevisiae feeds on sugars for energy, in the process producing carbon dioxide and alcohol (this is fermentation in a nutshell). The carbon dioxide bubbles get trapped in the dough, creating the lift that makes the dough rise. The alcohol, meanwhile, evaporates when baking, transforming into gas that also contributes to the rise of the bread. The alcohol, along with acids produced during the fermentation process, impart that wonderful flavor and aroma associated with yeast-leavened breads.
What are the different kinds of commercial yeast used for baking?
There are three main types of commercial yeast used for baking:
- Active dry yeast consists of live yeast cells that have been largely dehydrated under heat, leaving some cells alive and surrounded by the remainder of dead cells. Because the spent outer cells encapsulate living centers, active dry yeast must first be dissolved in a relatively hot liquid (known as “proofing” or “blooming”) in order to slough off dead cells and reach the living centers. Active dry yeast can typically be found in the grocery store baking aisle, next to other dry ingredients like flour and baking powder.
- Instant yeast, sometimes called bread machine yeast, is another type of dry yeast. It has smaller granules than active dry yeast and does not need to be proofed before using. It can be added directly to dry ingredients and rehydrates quickly when mixed with water. Instant yeast also has more live cells than active dry yeast, which means it works faster and requires less amount per recipe. Instant yeast can also be found in the grocery store baking aisle.
- Fresh yeast, also known as cake yeast or compressed yeast, is a soft block of live yeast cells that has not been dried or processed. It has a short shelf life and needs to be refrigerated or frozen. Fresh yeast has a creamy texture and a mild yeasty smell. It needs to be crumbled or dissolved in warm water before using. Fresh yeast is usually preferred by professional bakers for its superior flavor and performance. Fresh yeast can be found in some specialty stores or online.
How to use baker’s yeast in baking?
The amount and type of baker’s yeast you need for baking depends on the recipe you are following. Generally speaking, you can use any type of baker’s yeast interchangeably, but you may need to adjust the amount and rising time accordingly. A rule of thumb is that one packet (2 1/4 teaspoons) of active dry or instant yeast is equivalent to 0.6 ounce (17 grams) of fresh yeast. You can also use a digital kitchen scale to measure the exact amount of yeast you need.
To use baker’s yeast in baking, you need to activate it first by mixing it with warm water (and sometimes sugar or honey) in a small bowl. The water should be between 105Â°F and 115Â°F (40Â°C and 46Â°C) for active dry yeast, or between 120Â°F and 130Â°F (49Â°C and 54Â°C) for instant yeast. If the water is too hot, it will kill