brewer's yeast

Brewer's yeast is a living microorganism, Saccharomyces cerevisiae, a single-celled fungus historically selected and cultivated for its fermentative properties in beer production. The yeast consumes sugars during fermentation and produces ethanol and carbon dioxide as metabolic byproducts, generating the alcohol and carbonation characteristic of beer. After fermentation is complete, the yeast cells settle and are harvested as a wet sediment or dried into a fine powder.

Brewer's yeast differs from baker's yeast and nutritional yeast primarily in its ancestry and cultivation history—brewer's strains have been selectively bred for beer production characteristics such as flavor development and sedimentation patterns. When dried and deactivated for culinary use, brewer's yeast retains a savory, slightly bitter, malty flavor with umami notes. It is rich in B vitamins, minerals, and incomplete proteins.

Brewer's yeast is employed primarily as a nutritional supplement rather than a leavening agent in modern cooking, since the fermentation process has already been completed. It can be mixed into smoothies, soups, and beverages for its nutritional density and savory flavor. In some culinary traditions, dried brewer's yeast is used as a flavoring ingredient in vegetarian broths, cheese substitutes, and savory dishes seeking umami depth. It is occasionally sprinkled over popcorn or incorporated into dry rubs for seasoning, though its strong flavor profile requires careful dosing to avoid overwhelming dishes. Because it is already inert, it functions as a nutritional fortification rather than a leavening or fermenting agent.