Yeast at a Glance
Yeast is a living microorganism belonging to the fungus family. It has been used worldwide for countless years in the production of bread, beer, and wine.
Baker’s yeast, the type most commonly used in cooking, belongs to the species Saccharomyces cerevisiae. Under the right conditions, it has the ability to ferment: it produces carbon dioxide and alters the properties of other ingredients through the action of its enzymes. It is this fermentative power that makes it an indispensable ingredient not only in baking, but also in brewing and winemaking…
Different Forms of Yeast for Cooking
Pretzels, hamburger buns, ciabatta, pastries… Many recipes use baker’s yeast—more specifically, a strain derived from Saccharomyces cerevisiae—as a leavening agent. This yeast is sold in various convenient forms, designed for both professionals and home cooks.
- Active fresh yeast. Also known as pressed or compressed yeast, it has a crumbly texture and a color ranging from cream to beige. One gram of active fresh yeast contains 8 to 10 billion live cells. Sold in small cubes in the refrigerated section, it can be used directly in the mixer or after being dissolved in a little lukewarm water. Its downside: it only keeps for 3–4 weeks in the refrigerator.
- Active dry yeast. This type of yeast contains live yeast cells that have been dehydrated before packaging. The yeast must therefore be rehydrated in lukewarm water (about 35°C) to reactivate its cells before being added to the flour. In the form of tiny granules, this dry yeast is usually packaged in a resealable container.
- Instant yeast. This type of yeast is dehydrated but does not need to be rehydrated before use. It comes in the form of small sticks and can be mixed directly into the other ingredients in the recipe. Instant dry yeast is sold in pouches packaged under modified atmosphere to preserve its fermentative activity.
For seasoning your dishes, salads, pasta, or for making vegetarian pâtés, inactive yeast in flake form works wonders:
- Nutritional yeast, also known as “nooch,” offers a wide range of tastes (cheese, meat) and flavors (umami, salty). It has the advantage of being rich in protein and B vitamins. Note that nutritional yeast is not a leavening agent and cannot be used to make bread.
How should you store yeast properly?
As a living organism, yeast must be handled and stored properly to maintain its activity.
- Fresh yeast should be stored in the refrigerator at a stable temperature.
- Active dry yeast must be rehydrated in a little lukewarm water before use; water that is too hot can kill its cells.
- Instant dry yeast should be stored in a dry place, away from light, until opened, and then in the refrigerator in an airtight container.
- Finally, the best-by date indicated on the packaging of active yeast must be observed. Once past its best-by date, yeast loses its activity.
- Nutritional yeast should be stored in a dry place until the end of its shelf life. It is recommended to reseal the packet tightly to preserve the texture of the flakes.
How does yeast work in cooking?
In cooking, these microorganisms in their active form are primarily used for their ability to ferment. Fermentation is a metabolic process by which yeast cells convert sugars into simple products: a gas (carbon dioxide), alcohol…
Bread Dough Fermentation: A Two-Step Process
In baking, when yeast is mixed with flour and water, the enzymes in its cells break down the sugars found in grains. The air introduced during kneading triggers one of its metabolic pathways—the aerobic pathway—during which the yeast cells multiply and become active. They produce water and a aerobic gas, carbon dioxide, which causes the dough to rise.
Once incorporated into the bread dough, the lack of ambient oxygen causes the yeast to switch to an anaerobic, fermentative state. During this second phase, the enzymes in its cells convert the sugars into carbon dioxide and alcohol, which evaporates during baking. Aromatic compounds are also generated during this process. Fermentation therefore directly contributes to the texture, taste, and aroma of bread.
The Most Common Uses of Yeast in Baking
Baker’s yeast is used in many bread recipes: baguettes, sourdough bread, pretzels, pizza dough, hamburger and hot dog buns, bagels, paninis… It is also used in certain pastry recipes, such as milk bread, croissants, brioche, and cinnamon rolls… When incorporated into the dough of these products, it causes them to rise and influences their final flavor. Some people even add a pinch of yeast to pancake batter to make it lighter.
Other Culinary Uses of This Microorganism
This ferment is commonly used for many purposes in food preparation. In baking, as we’ve seen, yeast is used to make bread dough rise and to give it its physical and flavor characteristics. In brewing, the strains used in beer fermentation are responsible for the beer’s carbonation, flavor, and alcohol content. There are also homebrewing kits available for making your own craft beer. Certain cheeses, such as Camembert, are made using this microorganism to form their rind or develop their aromas.
Yeast also plays a role in food preservation. Historically, many products have been fermented using strains of this microorganism to extend their shelf life. This is the case, for example, with vegetables and condiments such as kimchi and soy sauce…
Finally, in extract form, yeast enhances the flavor of the dishes to which it is added: soups, salad dressings, sausages, vegetarian meat alternatives, and more…
Yeast: What Are the Health Benefits?
Yeast is used to produce staple foods, such as bread, which feed many people around the world. It contributes to the nutritional value of these products. For example, it is a good source of B vitamins, particularly vitamin B9. Through the fermentation process, it also helps release minerals found in flour, such as zinc and magnesium.
Nutritional yeast, on the other hand, is an inactivated yeast consumed for the nutrients it contains. Highly popular among vegans, the flakes can be sprinkled directly onto dishes, much like grated cheese. From kale chips to mac and cheese, nutritional yeast finds its way into many delicious recipes.
Innovations with Yeast in Cooking
Yeast continues to be the subject of extensive research, particularly regarding the development of strains capable of producing the most interesting flavor profiles. Research is underway to make these microorganisms more resistant to current preservation and transportation methods, particularly freezing. Finally, the craze for sourdough bread has also prompted researchers to identify yeast strains resistant to the acidic conditions characteristic of sourdough bread production.
From traditional baking to the most innovative culinary applications, yeast thus plays a central role in food processing. Thanks to its fermentative power, it shapes textures, develops flavors, and enhances the nutritional value of many everyday products.
