Beer yeast

Beer yeast is a type of yeast that is used in the fermentation process to produce beer. It is a crucial ingredient in the brewing process, as it is responsible for converting the sugars in the malt into alcohol and carbon dioxide. This process is known as fermentation.

History

The use of yeast in brewing has a long history, dating back to the earliest civilizations. The ancient Egyptians, for example, were known to use yeast in the production of their beers. However, the specific strains of yeast used in modern brewing were not identified until the 19th century, when Louis Pasteur conducted his groundbreaking research into fermentation.

Types of Beer Yeast

There are two main types of beer yeast: Saccharomyces cerevisiae and Saccharomyces pastorianus. S. cerevisiae, also known as ale yeast, ferments at warmer temperatures and tends to produce beers with a wide range of flavors and aromas. S. pastorianus, also known as lager yeast, ferments at cooler temperatures and produces beers with a clean, crisp taste.

Ale Yeast

Ale yeast is a top-fermenting yeast, which means it ferments at the top of the fermentation vessel. It is used in the production of ales, stouts, porters, and other types of beers. Ale yeast ferments at warmer temperatures, typically between 15 and 24 degrees Celsius.

Lager Yeast

Lager yeast is a bottom-fermenting yeast, which means it ferments at the bottom of the fermentation vessel. It is used in the production of lagers, pilsners, and other types of beers. Lager yeast ferments at cooler temperatures, typically between 7 and 13 degrees Celsius.

Role in Brewing

In the brewing process, beer yeast is added to the wort, a solution of malt sugars. The yeast consumes the sugars in the wort, producing alcohol, carbon dioxide, and various flavor compounds. The type of yeast used, as well as the fermentation temperature, can greatly affect the flavor and aroma of the finished beer.

See Also

• Brewing
• Fermentation (biochemistry)
• Saccharomyces cerevisiae
• Saccharomyces pastorianus